I think this is something similar to what you are looking for but maybe doesn't fit your dimensions. http://bundutecusa.com/cargo-camping-rigs/bivak/
The Rambox rack starts at $1999 from NutHouse. The removable crossbars add costs but are super stout and expensive to have fabricated.
Racks are all aluminum. The Rambox rack mounts to existing holes with new hardware for a no drill application. They are also ready built to except a retractable coiling cover. Textured hard cure urethane coating the rack.
RockBox in California does that too. Basically an M416 style.
I've seen them bolted directly to truck frames (in place of the factory bed), or slide in style in bigger full size rigs.
Andy,
I don't want you to think I'm trashing your product, because I'm not. I've seen your work and it's excellent. I just think, at this time, the cost is too high.
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