My spare tire sub audio build.... need some help!

Astrosfan

i havent had any issues with the box or false floor moving around. Im silply using industrial velcro to hold the pieces down, they are very light. they box sits pretty snug on the spare tire. I plan on using some dynomat to ensure its in there tight. I dont think it would come out during an accident. The box would first have to come straight up about a foot and only then could it move around freely in the back. The box is the least of my worries if i get in another accident.