Your going to find almost all RV's to be very difficult to full time in when you are dealing with New England winter type of cold.
Days are short, many areas are heavily shaded, all limiting your solar charge times.
There are folks that use them, but for the most part, trying to keep water tanks/pipes thawed, becomes too much. If you can perform all water related ablutions in your relatives homes, it's possible, but in something the size of a B your going to find it tough. Even safely heating it is difficult because while its a small space, they dont tend to be that well insulated and if you use something like a Camco Wave to ease the propane consumption, you have to be cautious about carbon monoxide.
It's not impossible, but it's not going to be easy.