I use to live in Mt. Pleasant and I don't remember any campgrounds there. We weren't camping back then so I might have over looked them. I know there are very nice county parks in Charleston County and I believe there is camping at the park on James Island. That is close to Folly beach rather than Isle of Palms. Good luck with your hunt. Off topic, but I highly recommend Jack's Cosmic Dogs and Seewee Seafood restaurant while you are there!