Been there a couple of times during the day but never camped. I know they have drive up campsites and hike in campsites. No fires allowed at the hike in sites. The drive in campsites are all in a row right next to each other.
Call down there and ask whomever picks up the phone how busy it is and if you'll need reservations. I've always had good luck doing that at different state parks and such. Usually pick up some good info and tips.