Seeing that the OP is from MI, I'd suggest having it done at the factory if at all possible, especially if its a laminated trailer.
In that case (laminated) I would not want some kind of half assed patch job from some mobile RV guy, or a body shop. If it's a laminated trailer and you boogered up the end of the sidewall, insist that the insurance company has the factory replace the entire wall. That's how its done, manufacturers install new sidewalls for delam issues under warranty all the time, and they all have service departments. It is not a band aid fix.