Stumbled on to this article and rig and thought there might be some interest/inspiration here. I don't have any more info than I link to below but if you find some updates please post.
"The finished product is a completely redesigned Dodge truck with an insulated, carpeted, rear sleeping area complete with lighting. On the roof is the snowmobile ramp with a hydraulic backend that lifts up for more room in the sleeping quarters. The front seats spin around so you can sit comfortably facing the rear of the vehicle. Itís not just for winter, either. In the summer, you can take the canvas off to enjoy the cool summer breeze."