If I could find 2 pop-up camper fiberglass tops. One for a base, One for a roof, Mounted them on a 2x4 plateform (steel) Using my stake pockets and cross braces, Attached Canvas to the upper and lower shells. And the locking system in all 4 corners (Think fold out table leg's just heavier duty) In all 4 corners.
It would be low profile, Allow for alot of bed storage, fairly light weight, Easily removable with the slide in bed camper jack's. And shouldnt be stupid pricey sense you can find pop up campers for free on CL.