Living in an RV in New York City during winter

Solar would give you something during the day; not as much as noon in sunny Arizona, but maybe better than nothing. Harbor Freight has a complete 145watt setup for $150 - you may want to get a couple of them or get a higher quality solar unit to squeeze every bit of electricity out of what sunlight there is. Charging batteries takes a long time - running a generator for 2 hrs/day is unlikely to get them fully charged. An extension cord to a friendly house would be your best friend.

Good luck.