Fort Charles, and yes I agree it's a bit creepy. Especially when you know that people live just on the other side of the dune...
Was on the beach for 3 days and seen 2 people. If people seeing you c/o makes you feel creepy, it is an option to be clothed also. Its a beautiful beach worth checking out, and the town is VERY peaceful, which reminds me of Negril when I was there in the 80's.