Definitely a UJOR conversion, nice isn't it!
I wonder if the positive of having a lifted 4x4 LWB (158") outweighs the cons of such a longish wheelbase. I mean, with that setup and mud tires you'd think they are looking at hitting some of the trails but that thing would be a PITA to turn, easier to get high centered... Especially compared to a similar setup SWB (138").
I'm asking and would love the actual owner's opinion 'cause I'm preparing to build a similar vehicle. I've been exclusively looking at the regular E350 ambulance (138") but a very clean LWB just came up for sale. The overall length is not much longer. What you get in return is an extra foot of interior space and less rear overhang (7" or so less) for the LWB.
2008 E350 Hambo
2001 E350 AmbuLand (sold)
1970 Econoline popup camper
1965 Econoline Travelwagon
A few bicycles...and sandals ;)