


A service body is much more expensive than a flatbed. An aluminum service body is rare and would be very expensive.

It's a little surprising that someone hasn't come up with a camping-type utility bed specifically designed for off roading or "overlanding."
Think about it: Make it out of some kind of modern fiberglass or plastic to save weight. Include an enclosed rear area for sleeping or secure storage, and then have the compartments on the outside available for neccessary gear.
As with many things, though, the drawback would likely be high cost and very limited market.