We have tried, but never found anything.
You have to choose, either proximity, or amenities. We haven't found anything with both.
Liberty Harbor RV "resort" is in NJ and there is a ferry stop in the campground that takes to Manhatten in about 10 minutes, but it is really nothing more than a parking lot with hook ups. Spaces barely wide enough to open your slides. We stayed here many years ago with a much smaller trailer. I am not sure I would even try it with my current trailer.
When we did a trip to Main, we stayed at Black Bear Campground in Florida, NY. Nice enough place. The sites were not bad size wise, it had a clean, well kept pool, and putt-putt. BUT it is an hour and a half by commuter train to the city.
I will be watching the thread to see if anyone else knows of some place closer because we want to head back up there next year.
2016 Sunset Trail 33BD
Tow Vehicle 2016 Nissan Titan XD 4x4, Crew Cab, SV with Cummins V-8