If you plan to visit New York City, then you’re not going to have much choice. If heavy traffic is a deal-breaker for you, then the northeast corridor between Washington and Boston could be problematic.
That said, you can avoid the busiest routes by staying at Croton Point Park as mentioned earlier. Info is here:
https://parks.westchestergov.com/croton-point-park.
The Metro-North Croton-Harmon train station is right next to the entrance to the park, and it’s an easy (and quite scenic) one-hour ride along the Hudson River into Grand Central Terminal in Manhattan. Train schedules and fares are at
https://new.mta.info/agency/metro-north-railroad.
Liberty Harbor has its fans. If heavy traffic doesn’t bother you, it’s very convenient - 15 minutes to lower Manhattan via the PATH train. But that’s it’s only amenity; it’s a concrete parking lot with hookups.
Note that the only river crossing in NYC that allows travel trailers is the George Washington Bridge (I-95). No tunnels, ever. And in NY and Connecticut, stay off any road that has “Parkway” in its name. You’ll risk a ticket and the loss of your Airstream’s air conditioner.
I-95 through the Bronx heading up to New England is probably the worst you’ll encounter for towing just about anywhere. But it’s not impossible; I lived in NYC and towed that route for years before we moved south. It takes good nerves and the realization that the traffic actually helps because it slows down the flow. You’re much less likely to have an accident in traffic at 20-30 mph than at 65.
You can avoid all that if you stay at Croton Point Park, except the parkway restrictions—that still applies.
Jim