If you have a self-contained RV (no pop-up/canvas; permanent toilets/water tanks), like the beach, fishing, boating, and/or windsurfing, this may just be the park for you. It is nothing more than a parking lot with no hookups and only composting toilets available, but you get access to Block Island Sound and all that it offers. Sites 58-75 are waterfront. For Rhode Island residents, the price can't be beat, and it's fair for out-of-staters, too, because of the location
No animals permitted. Generators only 8a-8p. Clam shack, marina, deli, and ice cream place nearby, but I doubt you'll want to fight the traffic on a summer day.
You can't really beat the price and location combo of Charlestown breachway. There are no hookups or even a dump station, but your site may overlook the channel and is only a very short walk away from the beach. There are toilets; only RV camping is allowed, and the units must be self contained. Stay as long as you can, then you can dump and refill your water at Burlingame State Park for free with registration and the breachway.