I have a flat bed I had built and instead of all compartments, I went with under bed storage for permanent things, air com, tools jacks and on Sides full length al w 2 doors so there is full room to put long, short or what ever, More storage than I...
I have a flat bed custom build on f350srw w lance. 950 s. flat bed I same size as orig bed an built so it is same height as bed o keep cab overhang correct. I fitted sides w al sides w 2 doors per side that are attached through side stake pockets....