Liberty harbor CG is probably your best bet, never been to, but as far as convenient to lower Manhattan, that's the place. As far as bringing a 5th wheel into nyc, specifically Manhattan, total total mistake!!! the roads are congested, other drivers are very impatient, turns are tight, and pedestrians everywhere.
Liberty park to the path, (port authority trans Hudson) is a train shuttle that runs froim NJ into several spots in Manhattan. Its a great deal, and depending what time you want to travel, there's always a train loading. Best of Luck, Have a great trip!!
Kevin
FMCA #F383349
2006 Monaco LaPalma
2015 Hyundai Elantra