When we used to head south in January or February these are the ones we saw as our options.
If you are going down I-75 Harbortown RV Resort in Monroe, Michigan advertises as being open all year round. Can't comment on the place as I have never stayed there.
The KOA at Bluffton/Findlay, Ohio is open all year round but there is no water, no comfort stations, no dumping stations and no one in attendance. I only use it as a last resort.
Our favourite is Kentucky Horse Park, just north of Lexington, Kentucky. The sites at that time of year are electric only but there is water available at the dumping stations. The comfort station with showers is clean, large, heated, and open. It's a bit of a long day for us but we head out real early the first day.
South of Lexington you will find many places are open all year round. When we used to travel at that time of year I have de-winterized as early as Kentucky Horse Park and as late as Southern Georgia. It is all weather and forecast dependent.
This may start a whole bunch of comments but out of the two most popular routes to Florida from our area I prefer I-75, especially at that time of year. It is about 100 km. longer but you have more 3 lane sections and the total elevation is not quite as high so you have less chance of running into surprise severe weather. I take the east bypass around Cincinnati because of construction and road condition but I go straight through Atlanta. You are from Toronto so Atlanta will be a piece of cake. There are other ways to get there but this routing is purely my preference.
