I recently saw an announcement from the National Park Service about them expanding the camping capabilities at Floyd Bennett Field, located in Brooklyn, New York. It's mostly tent camping, but they say they have sites for six RV's (dry camping).........with future expansion plans.
Of course, I don't know large of an RV you might can drive/pull thru New York to get there.
Just passing the info along for those who may want to try it out.
Gateway National Recreation Area - Camping at Gateway (U.S. National Park Service)