I like the idea and can only think price and maybe weight is why we don't see more set-ups like that.
There is a company in Salt Lake City that makes "utility beds" not boxes. Their bed has all the drawers and boxes of a utility box, but keeps the lines of the pickup bed. From 20 feet away it looks like a regular bed. I think something like that would be well worth the weight and would really compliment either an ARE utility topper with a sleeping solution or a FlipPac, Four Wheel Camper, roof tent, etc.
Lots of fun options still out there like this
Ute tray and canopy idea -
When you're building your outfit, your imagination and budget are your only limits!