FWIW, another campground review from our first trip south. Putting it here because it's near St. Augustine.
Pellicer Creek Campground on Rt 1 just south of where it crosses I95. We stayed here 3 nights mostly just to break up the trip from Hilton Head to Lake Worth into 2 legs. It got good reviews on rvparkreviews.com and I can see why. It's a fairly small park (30 sites or so), some pull through, some back-in. The people who run the place are friendly and the park is well maintained. We paid $39 a night with a Good Sam discount for a full hookup and satellite/cable (get a box from the office).
It's not really near St. Augustine without some vehicle, but if you're into kayaking or canoeing, the creek is on property. It is close to Rt 1 and there is some road noise (not really mentioned on rvparkreviews), but once it fades into white noise it wasn't an issue. Easy to get to from I95.