You may have trouble finding something that has full service. One problem would be water freezing. They would have to have a freeze proof hydrant and you would probably have to run off your tank and fill as necessary. It would also be hard to keep the sever from freezing up, and also the water in your unit. We are from Sioux Falls, SD which is a little sw of where you are looking. A few of the parks in our area do have winter residents, but they have to make special accomidations to be able to accomplish this. Good luck looking.
Roger & Cheryl Full Time since 2002, RVing since 1975 2008 Chevy 3500 Crew Cab Dually, 2012 RW 36RL