If you want to be as far north as Chiefland Florida, then I suggest you look at Strawberry Fields RV. It is brand new and already very popular among Escapees anyway. Rock Crusher Resort a bit further south is also very popular. Not near the beaches, there aren't any on that section of west coast FL, but near a number of excellent springs.
Suwanee River Bend is another great park but had no Verizon when we checked it out. The WIFI worked but the long term campers said it was unreliable.
Whatever you do, you better make reservations PDQ.