Private parks that wish to restrict the age of coaches typically will apply the restriction to all coaches. If I am making a special trip to a destination park that restricts age, I always ask in advance if my coach will be acceptable - - so far have only been turned away once in four situations (when towing my '64 Overlander with '99 GMC Suburban) - - the reason for the turn-away was lack of a permanently mounted gray water tank. When I am traveling and selecting parks without prior arrangments, I simply pull into the waiting area and proceed to the registration desk - - if I am asked about the age of my coach, I tell them that it is a fully-restored 1964
Airstream - - usually, I haven't been questioned - - the one time that I was questioned, the park operator knew Airstreams and that mine was more than 30 years old due to the front window style, but he welcomed me despite the posted rule.
So far, I haven't encountered very many problems related to parks with coach age restrictions but I don't travel frequently to either coast where these restrictions seem to be somewhat more prevelant. My nagging concern is how parks might react to my 1975 Cadillac/1978 Argosy Minuet combination next summer on my route to the International Rally in Vermont - - both vehicles are well-maintained originals with very minimal restoration (especially on the exteriors).