Our first RV was a 77 Barth, a big tin breadbox on wheels, which we had for 5 years before getting the Interstate. It was a great grandma-and-grandpa-mobile, but not very roadworthy. We cut our eyeteeth on it, and had a lot of wonderful times with small children, though, so it was worth every aggravation it gave us.
We got some hard looks
driving it, but were never turned away from a campground. Some of those looks
were from law enforcement, wondering if we had a rolling meth lab or other illicit activity going on in there, I suspect. Once they would see us, though, we never had any trouble and were never stopped or searched. We were always neat and tidy, too, which may have helped our oldie in those rather snooty RV parks. You know, the rattlettrap RV's with all the papers and junk on the dash? We weren't one of those.
More and more places are asking the year of your rig when you register or call in for a site. Personally, if a park requires, sight unseen, a certain level of "newness" to be in their park, it wouldn't likely be a place where we'd want to stay very long.