yeah looks kinda thin, haha its just the angle the pic was taken from, its equal distance on both sides... i had some 5/8 board kicking around so i used that, could'nt justify spending the extra cash on 3/4... yes it's a fully enclosed sealed box, the lower right section was just constructed to make the box fit to the shape of the truck... the actual enclosure is only down to the bump in the floor..