I have a set but am holding on to them until I sell the camper in case the next owner needs them. They are pretty hard to find and become harder every day.
I am assuming he is carrying the 815 on a short bed truck. Hopefully at least a 3/4 ton because the unit gets to be pretty heavy when all loaded up. Last time I ran across the scale I had 3,500# between the camper, stuff inside, and what I had on the back seat.
A set of sheet metal boxes is probably going to be about your best bet. The boxes need to house the tail lights, a side market light if you use flush tail lights, and have a wing that goes far enough forward to obscure the truck's tail lights.