We're in S/E Michigan also. We've traveled in the winter to Florida and have stayed in the camper. Run the furnace a couple hours before you want to stop and bring some warm blankets. Take a generator and run a space heater if you have it. We stop at Walmarts, go inside and do some shopping and use their bathroom and with their permission, we stay in the trailer in their lot. We travel I75 also and are headed to Florida the end of March and make the trip in 2 days.
I bought the book "The Next Exit" and it has come in quite handy.