I have seen so many different things done with a PU. First off you can re-canvas them.
I have seen them turned into hardsided campers for regular summer camping, ice houses for winter, and hunting shacks, also utility trailers. My favorite conversion was a cook shed, used primarily for a family reunion.
For the cook shed, they pretty much gutted it, removed the canvas and bunks. Added stainless steel counters (over wood frame), locking cabinets underneath to keep larger critters out. Huge diameter PVC pipe mounter over the rear bumper, for a grey water tank. Had a nice sink, multiple stoves, big girdle, etc. It was a late 60's early 70's PU, they pulled it with a very new large expensive class A diesel pusher.