There is one in south Louisiana, below is their site , WITH pics!
I remember jackass or wildboys doing a show there once and playing volleyball or somthing nekkid with some not exactly attractive folks.
And no, I have never been. They are in the brochures that state has for camping though. For some entertainment, go to the site and check a few of the pics, you are guaranteed to feel better about yourself. Their rules are also hilarious!
Warning, there are nude pics on this site, so it is not exactly work safe.
Indian Hills Family Nudist Park