We have begun installing the sides on the frame. For this job we have chosen Sika 252 adhesive. The frame got a random da sandinging, then activator was applied. We went one step further and used Sika primer to ensure good adhesion.
We chose this route over welding for a couple of reasons. Aluminum can crack over time. With flat sheets glued over entire frame, the panels act as a structural member, thereby reducing the chance of a crack. We chose .190" thick aluminum for the exterior panels-dent resitant and structural. Further, we have seen the results of welding aluminum sheets over aluminum members. Its always leaves a "tatoo" on the exterior panel. It warps the panels as well. Gluing the panels to the frame eliminates this and leaves a nice smooth finish that will show better than fiberglass.
Note: the rear overhang is designed to reduce the low pressure zone at the rear wall off camper when speeding down the highway.
Pete