I live in upstate New York -- not far from the Canadian border and SUNY Potsdam. ALL private campgrounds here close by Columbus Day weekend. They do NOT remain open in the winter because of freezing water and snow issues. There is one state park that remains open until the end of October, but that's it.
Last year we wintered in our RV in Branson, MO. There were occasional days when temps were 18 degrees (above) and our water and sewer lines froze. On those days, we called home to talk to our sons (who remained in our home all winter). It was frequently 28 degrees or more below zero in upstate NY with wind chill factors of negative 40. There is NO WAY you would be able to stay warm in a trailer, regardless of how much insulation you tried to add.
I have seen apartments advertised in our area for anywhere from $600-800 a month, often including utilities. By the time you spend enough money to make your RV somewhat livable, you will have spent well over the total it would cost you to rent.
Also, this year is predicted to be especially cold, snowy, and long; starting earlier than usual and ending later than usual. In fact, our first snowfall has been predicted for late September!
If you actually decide to do this, make sure you keep your vents clear of snow so you don't die from your propane gas.
