RV Parks w/older RV restrictions

I've heard that some commercial parks have a 10 year rule. Although, I've never come across one. But, my preference lies in government parks that offer a natural ambiance and larger sites. On the rare occasions where I've stayed in private parks, it's either been in a Passport America park for a night or two, or a monthly rate at a "mom and pop" park that meets my needs at the time.