Living in the South heat isn't as much of an issue as having to much heat. I have an AC unit that keeps my room at 80 degrees in the summer and I just use oil filled heaters and fans to keep it at 80-85 in the Winter. That coupled with the heat tape works great for me. I can even open a window or two in the winter with it freezing rain and spiting snow and not have a problem with the temps. .

Spend the extra money do it right the first time and don't worry about it.