Thanks for all the helpful comments. I've been doing a bit more research on this and it seems that every suggestion I've heard is usually discredited by someone else
The park I'm at is in the desert so pack rats are a natural problem and they will always be here. The management cull the rats and destroy the nests whenever they are found in the Park, but there have been several vehicles damaged.
The current preferred solution seems to be to discourage the rats from approaching the vehicles by surrounding them with LED rope lights on the ground controlled by a dusk-dawn timer. I'm told that pack rats are nocturnal and won't approach the lights. Most of the damage seems to be in engine compartments where the rats build a nest and seem to like to chew through the wiring. These rats are LARGE so it's unusual for them to get into RVs and trailers, but it's still recommended to do a thorough inspection of the underbelly to close off any holes they might use.
I've bought some of these rope lights (WalMart $13 for 16' sections, $12 for outdoor timer and light sensor switch) and a local mobile RV Service is doing the prep work to close off obvious points of entry, plus they'll do a monthly inspection in storage to check status.
Thanks for the input.