JeremiahBrown To me, it looks like he uses glass on the front- and nothing on the backside. In my eyes, this is not a good example, as it contains a lot of trapped air.
In your case, I would glue the cells directly to the surface of your camper. Depending on the bonding strength of the solar silicone, this could be done in one step. Some hard and at the same time light transmissible and UV-resistant material needs to be put on top. Polycarbonate is my way to go right now. I would use something like 0.5 or 0.3mm. This adds a good cover without adding too much weight.
There is also another option called Plexigals-Sun, but this does not seem to be available in small quantities only as a direct order from the manufacturer. Additionally, they only produce it in 5 and 3mm which will add a ton of extra weight.
Epoxie is susceptible to UV light. The result is rapid discoloration. The discoloration then blocks light and kills the efficiency of the cells.