At one time Sportsmobile was going to import bodies from ATW in Australia. Not sure how many were ever built. I walked though one, certainly impressive.
I don't understand what you are asking. Earthcruiser makes full rigs, and chassis. Phoenix makes full campers. TC makes shells. These are all quite different.
YouTube is full of Box Truck Conversion videos. Some good, some bad, some ugly. All are fun to watch.
With Mitsubishi pulling out of the NA market I don’t think I’d spend tons of money on a full blown expedition fit out. A simple cargo box conversion could fit on another vehicle platform.