We have camped in all 12 months in Michigan and never been cold or without a place to camp. Usually snow on the ground in January but it's usually light fluffy snowfall, not ice or icy. also Been in Tennesee evry winter since 1965 with an RV and froze our but off a few times as it's a wet cold feel and have had ice storms so you'd stay put a couple times already if smart. Especially in eastern Tennessee I-75 when we used to go that way to Florida to visit family. You don't wisely go down to Florida in the summer with it's very humid and sticky sickening heat.
Won't forget late December in the Nashville area on I-65 as it was like on greased roads even at 20 mph with inches of freezing sleet and snow on them and was even rutted so you didn't wander or else. Scary as heck!!! We had to overnught in a Mcdonalds truck/RV parking lot and the next day too as they don't really plow the roads like up north where they are kept plowed. Thus, we feel the true season for RV camping is quite bogus as to region stays.