Adding Storage Space on a Camper Trailer

This is a great project under $100 for those who like to hook on the camper first thing in May until around Labor Day and spend nearly six months of weekends and days off enjoying the beauty and charm of nature.

With two ammo boxes varying between $15 to $30 in most military surplus suppliers and 4 square U-bolts, you got yourself a project that you can complete in a couple of evenings while enjoying the campfire (Fig. 1).

This is not to say that RVs and campers don't provide you with enough storage space. We're all very aware of the efficiency put into those homes on wheels and how efficiently every cubic inch of the camper or RV is expertly rendered into use.

When it comes to storing hoses, though, it seems that even though there is space planned underneath for their storage, it may not be as appealing as it seems.

What we're talking about, here, is storing camping supplies, all your sewage hoses, and fittings inside the same space shared with your water supply hose, therefore creating a possibility that the wastewater from the sink and shower drain, as well as outflow from the toilet, could create a possibility of contamination to the drinking water supply hoses and their fittings.

Adding to this inconvenience is the fact that you might need to extract some camping goods from the storage area in order to reach access to your hoses and install them as you're setting up your camper.

It's easy to appreciate the ease of access to the water supply hoses from one container and the sewage hoses from another container, both of them just providing the necessary space for their intended articles.

Getting the Right Supplies

The first thing you want to make sure of is the availability of two ammo boxes of the right size. This fact makes it easier to choose the right ammo boxes from a local army surplus store or a local hardware supplier that carries ammo cans.

The fact that they are narrow and long makes the job easier when it comes to drilling holes close to each extremity to provide more stability to your mounted ammo can.

Step 1

Consider how you will secure the boxes to the rear square bumper. The best system that will not alter your bumper with welds or drilling is using square U-bolts 4-inches wide that will wrap around your square bumper.

A good size to look for is the 3/8-inch dia. square U-bolt 6-inch x 4-inch. The 6-inch length will provide enough material to trim to the right length later (see Fig.4 in Step 12).

The diameter of the bolt will determine the distance between the two center marks for drilling through the box—the bolt listed here would require 2 holes at 4-3/8 inches center to accommodate the installation.

If your bolts were at 5/16-inch dia., your center marks would then be at 4-5/16 inches apart. Also, since the bolts will be secured "inside" the box itself with washers and nuts, make sure to choose boxes at least 1-inch wider than the bumper—1/2 inch on each side to allow for the bolts to come through and the nuts to be screwed in.

Step 2

Gather up all your sewage hose together along with all of its fittings in a pile about 17-inches long—or whatever length of the box you want to fit it in. In our exercise, a 40mm ammo can measuring approximately 17-1/2 inches long by 10-inches high and 6-inches wide is shown in Figure 1.

It was perfectly dimensioned for our purpose, with a top held on by 2 latches, one on each end.

Step 3

Follow the same procedure with the water supply hoses and their accessories to make sure here again that the box is large enough.

Note: It should be noted that these ammo cans are also available online and possibly for cheaper.

Step 4

It's now time to list every criterion that will help you choose the right box for your needs-

For one thing, it needs a minimum width of 6-inches. Beyond that, ask yourself what type of cover you want on your boxes box.

If you want the possibility of locking your boxes while you’re on the road or when the camper is stored for the winter, you might want to install a locking system such as the "Ammo Box Lock Hardware Kit", available online or at your army surplus store.

With a little creativity, you can also make your own, as shown in Figure 2. A removable cover will require twice as many locks as a hinged cover.

Step 5

Once you've acquired your boxes, get 4 square U-bolts 6-inches long by 4-inches wide. While getting the hardware, you should also get 8 lock-nuts (for Steps 20 & 21) to secure the assembly once all the components have been properly drilled, cut, and prepared.

Preparation of the Ammo Cans

Step 6

Secure one of your boxes steadily so that the large drill bit cannot propel it into a spin while cutting its way through the metal. It should be secured upside down on top of a workbench (or a picnic table in this case).

Step 7

Determine the distance between the centers of your U-bolt as described in Step 1 and mark their locations on the bottom of the box, at each end (Fig.3). Use a center punch to make an indent for each one of the holes to keep the drill bit from slipping from its center.

Step 8

Drill a pilot hole at each one of the marks using a 1/8 or 3/16-inch drill bit.

Step 9

Finish the drilling by re-boring with a larger bit about 1/16-inch larger than the diameter of the bolt—a 3/8-inch bolt with a 7/16-inch bit, or a 5/16-inch bolt with a 3/8-inch drill bit—to provide you with enough slack so that both extremities of the bolt slide smoothly in place.

Step 10

Remove the box and repeat the same steps 6 to 9 for the 2nd box.

Preparation of the Square U-Bolts

Step 11

At this point in the project, you'll need to mount the box in place temporarily with the U-bolts. Place the box on the bumper, then bring up the U-bolts through the drilled holes from under the bumper and place the U-bolt plates over the bolts.

Secure everything in place with 4 nuts, tightening the nuts with your fingers only, until everything fits snuggly together.

Step 12

Butt the end of your measuring tape right up against the top of the nut, inside the box (Fig. 4), and measure the length of the threaded end protruding inside past the nut.

Step 13

You can now remove all four nuts, the U-bolt plate, and the U-bolts from the box.

Step 14

Screw in a nut on each one of the bolt ends, then cover up the threaded part with masking tape.

Note: It’s important at this stage to have the original nuts that were provided with the U-bolts screwed right in so that when you’re done cutting the bolts and removing the burrs, unscrewing the nuts and removing them will actually help to reshape the damaged threads on the bolts.

Step 15

Secure the U-bolt firmly to the workbench as shown in Figure 5, and trace a mark at the distance from the end measured in Step 11.

Step 16

Cut each of the bolt ends at the mark with a grinder or a hacksaw, then remove the remaining masking tape and file off the burrs from the threads as shown in figure 6.

The heat generated while cutting the bolts with a grinder, however, will most likely cause the threads to curl back towards the groove forming the threads, misshaping the end of the bolts to an unusable state.

The misshapen threads now at the tips of the bolts and which no longer match the threads on the nuts would make it almost impossible to insert and screw in a nut without cross-threading it.

This is why you should add a nut on the bolt prior to cutting it so that it could then be unscrewed while reshaping the threads to their original form. But a nut is not a die designed to cut its way into a specific thread size.

This is why once a bolt is cut, it should be filed beveled to remove the burrs from the end. Filling around the edges with a medium or a fine-cut file will remove most of the largest defects, and a triangular or a beveled file could also help to reshape the threads somewhat.

But there will always be some imperfections left which you will correct by removing the nut already on the bolt.

Step 17

Once you properly filled off the end of a bolt, you can start unscrewing the nut that's on it until you get some resistance from the slightly damaged threads on the bolts—as mentioned previously, the filling will always leave imperfections.

You should therefore proceed carefully while unscrewing the nut until you meet some resistance. Add a drop of cutting oil now and then to lubricate and facilitate the re-shaping.

Do not force the nut through all at once, as this would damage both of their threads. It could even cause the nut to become tightly jammed to the point of becoming seized on the bolt and impossible to rotate or to move any further. Instead, as you get resistance, just slightly force it onto the damaged threads then rotate the other way screwing it back in.

Keep moving the nut in that manner, screwing it in and unscrewing it back out, applying slightly more pressure each time you unscrew. You'll be gaining a bit more ground every time you repeat the movement.

Just make sure that it is done in a steady gradual manner, screwing in when the tension increases, then unscrewing again back to the resistance until the nut comes out.

Step 18

Repeat the same process (steps 15-17) for all the square U-bolts.

Putting It All Together

Step 19

Get one of the boxes and place it on the bumper where you want it installed. Depending on your box’s type, remove or open the cover.

Step 20

Put a U-bolt through the holes at the bottom of the box at one end, wrapping it around the square bumper. Slip the U-bolt plate onto the bolts inside the box, temporarily holding everything in place with two of the lock nuts.

Step 21

Secure the other end of the box with a second U-bolt through the remaining pair of drilled holes through the bottom, the U-bolt also wrapped around the bumper. Install the U-bolt plate in place and use two more lock nuts to hold everything in place.

Step 22

The best way to tighten everything up is by using a ratchet and socket with an extension, as it will let you screw in the nuts from outside the box making it easier to torque the four nuts evenly when you're done.

Choose a socket that fits your lock nuts and a ratchet with an extension long enough to extend beyond the top of the box. Snap the three components together.

Step 23

Insert your socket onto the first lock nut and start screwing it until you get some resistance, then shift to the opposite lock nut.

Step 24

Insert the socket onto the next lock nut and again tighten until you feel some resistance—do not over-tighten yet!

Step 25

Go back to the previous nut and tighten it to the same light tension so both have about the same tension.

Step 26

Go to the other U-bolt and repeat steps 23 to 25 for this U-bolt also.

Step 27

Once both U-bolts are in place, use your socket wrench to go from one bolt to the next tightening each one about 1/4 turn at a time while trying to apply the same amount of torque on each one as you go.

Tighten up all four nuts in that manner until the box is solidly secured, while always being careful not to distort the U-bolt plates or the bottom of the box.

Step 28

Follow the same steps 19 to 27 to install the 2nd box at the other end of the bumper.

As mentioned earlier in this article, you might also want to add some locks to your new storage boxes. You can either purchase specially made hardware for padlocks online or at an army surplus store or if you have some scraps around the shop you might prefer to fabricate one of your own. s shown in Fig. 2.

You can now appreciate the final product from your efforts in Fig. 7.

For more information on campers and RVs and accessories, check out our pieces on “ Installing an RV Water Pump”, “How to Install an RV Access Door”, and “How to Adjust the Height of Fifth Wheel Campers.”