The closest beach campground for easy access to the songfest, that I know about, is at Fort Pickens. It's at the western end of Santa Rosa Island in the Gulf Islands National Seashore. There are two separate campgrounds there. Neither is actually on the beach - meaning you can't see the water from the campsites.
One of the campgrounds has 4 loops - B, C, D, and E. It's closest to the water of Pensacola Bay. There are a couple of paths from the campground to the Bay. The other campground is called A Loop. It's a closer to the Gulf side of the Island. To reach the Gulf you cross the Park road and walk a dune nature trail.
Reservations are made through Federal recreation, camping and tour reservation information - Recreation.gov
or you can call 850-934-2622. You'll find maps there, as well.
There may be other campgrounds in the Pensacola area that are on
the beach, as in beachfront. Since I live on Santa Rosa Island, just a few miles from Fort Pickens, it's the only one I know much about. We did our 2 night shake-down trip there when we got the RV last September. Otherwise, since we live across the street from the Gulf, we don't go camping at the beaches around here.
You might want to start a new thread with your question so more people will see it. Hopefully if there are other beach campgrounds I don't know about, someone will help you out.
Hope you enjoy our area.