Looks like New York max veh. length is 45'. State Towing Laws for RVs
Now, I think commercial vehicles have different rules and you might be able to go longer if you're going to go the commercial vehicle route.
'03 Freightliner FL112, 295" wheel base, with '03 United Specialties 26' living quarters, single screw, Cat C12 430 h/p 1650 torque, Eaton 10speed , 3.42 rear axle ratio