I've thought about this type of mod, which I think is very feasible. Maybe not an easy project, but feasible for not much expense. My idea is to build a cap out of two inch thick foam and cover with fiberglass, maybe inside too. The foam can be easily trimmed to the aerodynamic shape you are after, best with a heat wire connected to a step-down transformer.
For more info on building foam trailers(or parts of a motorhome), check out the Foamies section of the Teardrops and Tiny Travel Trailers forum (wwww.tnttt.com). It's loaded with useful information and many trailer builds.
Keep us informed.
DA
