I personally second the opinion that for a camper the LWB is nearly a must depending on your needs. I can also mention that a turbo is also very nice to have at higher elevations if you have the choice between your three Mogs. Also having the higher hp in combination with the fast axles is a very nice combination if you plan to travel longer distances and wish to maintain higher cruising speeds. :smiley_drive:
My U1300L is currently naturally aspirated - but I am planning to add a turbo in the next few months to increase the motor from 130 bhp to around 170-180 bhp. Here at higher elevations (Colorado) the lack of a turbo and the power / torque limitations it presents can make "safe" highway and interstate travel a little interesting at times. Once off the main roads at slower speeds I have no issues, but hauling ~15,000 lbs at elevation using main thoroughfares up and down mountain passes is a tall order for the stock naturally aspirated diesel (1986 stock NA OM352).
If you don't mind me asking - what engines and models are the three Mogs you own? As others have stated, this info really helps to form an accurate opinion.