If I had to be in MN for the winter, it would be in a house with very good heat. While the are a few RVs that are built to handle cold weather, I know of none that I would want to spend the winter in MN in. You have had a very cold winter. The company that I work for has three offices in MN and two in ND and I travel there several times a year, from May thru mid October, in May the weather is just starting to be ok.
I would think that if you spent a MN winter in a fith wheel the heat would be running day and night and you would also need electric heaters also?
I know people that spend winters in an Arcti Fox in Washington state but I would think that MN would be to cold. Good Luck and to bad that you just can't go to south Florida for the winter.