Attach vinyl plank flooring?

My garage floor is 16" below the foundation/house level, so I need a platform/stair for the difference. I made a platform, 2x6 frame with 3/4" ply top that is 4' x 8'. I thought this is safer than a small stair and makes it easier to go in/out doors.
I want to spiff it up and bought some vinyl plank click flooring to cover the ply. I've put in plenty of laminate in rooms, but I want to install a trim board around the edge of the 4x8 to be flush with the top of the vinyl. I know in rooms you leave a small clearance for expansion, but in this situation, I have a couple of concerns:
For such a small space, I don't want movement if I do leave an expansion space.
This is in an unheated attached garage in Maine, so cold is a concern.

Would it be OK to just lay it in place with a small expansion space, maybe 1/8"? -or- I thought of using a silicone adhesive every couple of feet to keep it in place?

 

You need to get a laminate flooring stair nosing that matches your floor and use that as the perimeter trim, mitering the corners. You will silicone the perimeter and press the nosing into the silicone, using tape and/or a few weights to hold it in place for 24 hrs or so.