The NY Times Frugal Traveler has a nice writeup about what it’s like camping at Brooklyn’s Floyd Bennett Field out in Jamaica Bay. Yosemite it’s not. Apart from a pretty colorful description of the bathroom situation it does sound like FBF might we worth checking out if you have kids or if you really want to take the subway to a campground (though going rogue in Prospect Park might be a better bet).
My only experience with FBF was riding by on my bike on the way to the Rockaways. In the summer the fields fill with various events including some pretty well attended cricket matches.