Hi there,
I hope this fits your need.
1. Cape Cod Campresort & Cabins - Cape Cod, Mass.
This family-friendly campground features 230 sites on 55 acres, including spacious premium sites for RVs up to 40’ long. It is only 5 miles away from Buzzards Bay and the Vineyard Sound, and it features its own private freshwater lake with a sandy beach.
2. Blue Water Key RV Resort - Key West, FL
The private resort is situated on a small strip of land, so campers can find soft beaches and warm Caribbean waters right at the foot of their campsites.
3 Rivers End Campground and RV Park - Tybee Island, GA
Situated on the coast of Tybee Island, River’s End Campground and RV Park is a family-friendly campground just minutes from the beach.
It features over 100 sites with a mix of full hookup, water/electric and primitive tent sites. The park offers complimentary Wi-Fi, and it boasts the largest swimming pool on the island.
I hope those are good options. Remember to always bring all the equipment and spare parts for the interior here https://parts.mopargenuineparts.com/ needed for the RV you are renting and travel. Also please be careful you might get infected of Covid 19 outside.