driving up and over is not the problem, the wheels will sit right against the front of the wheel wells when in its proper place, with the alminum floor, you cannot get traction to back back out and I will not have room to pull forward to bump back over them, they act as wheel stops. So I am gonna build boxes in front of them that are level with the wheel wells so I can just back out. It still allows plenty of room height wise for the bunk head room. I am just doing wood ones temp so I can get my measurements, have not picked up steel yet to build pernament ones, I have plenty of scrap wood laying around from redoing the deck railing in the back yard so it is not like it is a waste of money.