One of my favorite places is Holiday CG at Panacea, Fla. It's right on Ochlockonee Bay. Most sites are close together but that's standard with older campgrounds. Weather will be the same as at Steinhatchee and Keaton Beach. My experience at that time of year is that you could have nice weather or freeze your posterior off.
You can go over to St. Marks and down to the St. Marks NWR and lighthouse (no entry), eat at the wonderful dive joint Outz Too at Newport, eat (great!) again at Huttons Seafood food trailer at the intersections of US-98 and US-319, and go to the beach at Mashes Sands or Bald Point and watch the water slosh.
As for party potential it'll pretty much be limited to Outzs with the bikers on weekends.
Holiday Campground - On Ochlockonee Bay,