Hi!
The permits are filled out by hand in person when you get there so spots are first come first serve. We headed towards Mt. Pleasant, there are a few beaches a really great one at Fort Moultrie
Sorry Kat but we did not go looking for beach access.
We only needed to email the ranger on the Santee Coastal Reserves website and ask. We got a really quick response it was open and we were allowed.
I hope that helps
Happy Camping!!