Be wary of taking I-287 over the Hudson River. The Tappan Zee Bridge can be a parking lot at certain times of the day and year. And now the bridge is under construction to be replaced, so it could even be worse. When I travel for work from NJ to Hartford, I always take Rt 15 (Merritt Parkway). I think since the road is a parkway it has restrictions on commercial vehicles, but I'm not sure about RVs. Some of the overpasses may be low. Additionally, there are sections that have sharp curves with little to no shoulders. I would think that would lead to a white-knuckle experience towing a TT.
The downside to I-81 through PA and on south is the amount of truck traffic. And much of the highway is only two lanes in each direction, so you tend to get stuck behind trucks passing other trucks in hilly sections. Make sure you have good sway control! :)