With a short box you could still put a 8' camper on with the tailgate down. I had a 10' Sun Lite Condor popup on a 8' bed with a L-shaped 100 gal gas tank. I notched out the bottom front of the camper so it would slide over the bottom section of the gas tank. I made side hatch doors between the camper and the cab and used the top of the gas tank for storage.
Used this setup for a 13,000 mile trip to Alaska. We had a porta-pot toilet. This was the perfect rig for us on the trip.
I bought the TC with damage to the top. Water had rotted some of the edge board around the top but the canvas kept the bottom dry. I liked the low profile and center of gravity. With a used unit I would be concerned with condition and price.
Good luck finding a nice one, I'm sure you will enjoy it.
