I haven't actually gotten it on the truck yet, but I am currently in the process of refurbishing a '73 Alaskan camper (10', noncabover) that will go on my 88 F350 4x4 (regular cab, single rear wheel) with a Stahl service body. The service body and the camper were not meant to work together, but I think it can be done.
There are two primary issues:
First, the service body bed is exactly 4x8. Narrower than a stock truck bed. Alaskans can accomodate this because the actual footprint of the camper is 4x8, after removal of the behind-the-wheelwells storage boxes. Generally, these boxes are just bolted on, so removal isn't a big problem. In contrast, I believe modifying a Fourwheel camper to be just 4' wide would be harder because you'd really have to narrow and then reconstruct the basic structure of the camper lower walls.
Second, the service body sides are too high. This is one reason I opted for a noncabover (and another reason its an Alaskan and not a 4WP--as far as I know there isn't a noncabover 4WP). The cabover section would have been alot higher than the cab roof--too high, I thought. Would look funny and poor aerodynamics. Anyway, the solution is a 6.5" tall platform in the truck bed, under the camper. I'm right at the point of building that. It would be slick to use the space for storage somehow but it will certainly be easier to just build the platform and be done with it.
Other thoughts: there are service bodies that have sides that are not any higher than the stock truck bed sides. Some of them are special builds (ala first Bill Swalls truck) but I don't think all of them are. I've seen some low service bodies on actual service trucks. That would be the way to go if you have the budget to buy a service body new. Also, the top-half of the Alaskan is exactly the same width as the service body on my truck. It will not hang out over the edge, as it does with a standard truck bed. I'm glad for that, but I did have to relocate a few connections (water, DC) that were originally mounted on the underside of the Alaskan's outside panel.
Hope that helps. I did alot of research about the camper-service body thing and didn't find much.
Blair