Why not remove all sharp edges, fill everything with air, and pad the floor, remove the gun shaped things, and have them all shoot lasers at each other?
Bed liner? You do know that costs about $50-100 a gallon.
Hell Survivors in Michigan has a lot of old military hardware out on the feild, and it hasnt been given the toddler treatment. Hell, they try and keep you out of the backs by tossing in jumbled old lumber.