You will have a hard time building a expo camper on a rear bed that short. What you really are looking for is a rare doka ambulance or doka long bed. Every one I have talked to or read a article by always wanted 2 more feet of living space in the camper box. Dont get me wrong it can be done but it gets to a point where its a sardine can on a rainy day. Also just buy a old truck and slap a plow on it, with rust and other issues you will be way ahead by not trying to do it with a camper. A unimog is a special piece of equipment if you are not willing to learn every part of it and do it yourself, you will be broke paying others to do it. You cant go to napa to buy parts most of the time.
Warren in SLC
1976 Unimog 416.163 Doka(PEQUOD)
2002 F350 crewcab PSD POS(DD)
Expo trailer- under construction
1955 dodge truck-under construction