Ok so here is what i came up with. The red represents the floor, I can buy a stock sheet 4x10, Im thinking attach it directly to the ribs with foam underneath, and bending 1" lips on each side to attach the side work to. The blue represent the insides, which will be rod lockers on the top and have minimal storage below the rod lockers, I originally thought i could make doors underneath and house 2 deep plano boxes attached to the door so when they open the trays are accesible. Still working that part out. Doing it this way, everything will be sheet product with bends, no structural tubing etc.