Scraped roof on low-hanging branch AARGH

It is possible that a lawyer can send them a letter threatening a lawsuit to cover damages,  or, your insurance carrier might want to subrogate a claim against the KOA.

If you were on any of the main roads or spaces that are made for RV's, it seems to me those areas should not damage an RV. A low hanging branch on the main road or over an RV space should be removed or trimmed before it damages a customer's vehicle.

If you somehow drifted off the main road or backed up too far, etc, then yes, it could be considered to be your fault.

If you have a dealer repair it, they should do so in conformity with OEM specifications.  The insurance company (depending on the language in the policy) is responsible for paying to restore the trailer to it's pre-accident condition, using factory specified roofing materials.  If the dealer says they can do it, just make sure they put it in writing.  Rather than fretting about what the roofing material is, let the dealer, who already has a relationship with FR, sort that out.  From what has been said so far in this thread, they are going to replace the roof membrane, which will of necessity, require them to source the material from FR or their suppliers.