"Another case of why are you asking us schleps on the internet and not just doing the logical thing…."
^^^ That....but since I'm adding my schleppy $0.02: The rule is that an RVIA # is required, not if RVIA is valid, worthwhile, the same as USF or NFPA, or makes sense. If the park requires an RVIA #, either don't go (because you don't comply) or call and explain the situation and see if they'll give you an OK / waiver over the phone. The value or legitimacy of an RVIA # is not the issue; the issue is that the Park has a rule...either comply with it or seek their waiver.