I have attached the NH Fish & Game link to OHRV/Snowmobile rental agents in NH & nearby Fryeburg, ME.
There are three NH agents of interest in the Conway/North Conway/Bartlett area and one just over the border in Fryeburg.
Town & Country is a very reputable dealer and right on Corridor 19 for some great riding right from the dealership!
Snowmobile Rental Agents