The basic rule is simple: if it's called a parkway in that region, RVs are not permitted and often are physically too large to navigate the road. That does indeed mean your routes are somewhat limited. The only exception of note is the Garden State Parkway in New Jersey, which is fine for RV travel. (RVs are also permitted on the Lake Ontario Shore Parkway west of Rochester, NY, but that's not exactly in the area...and frankly you're just as well off avoiding it as it's rather poorly maintained and the pavement is pretty rough.)