As a sun loving Florida lad, I had the joy of doing OCS(and boot camp too) in the winter. It sucks, but I suspect TBS would be worse if say you had to do O/D week. They take good care of the candidates at OCS, and I pretty much wore civilian(but black) gloves and quite honestly my hands were the only parts that ever froze. You'll have polypro, sweatshirts,tshirts, cammie blouse and gortex and will not really freeze. You could put on just about anything civilian under your cammies, the only rule is if they decide they don't like you you will be writing lots of essays at night if they catch you.
Now "Frozen" Fox company over at TBS, I hear that they have a certain %age that has to come down with frostbite/hypothermia before they are allowed to come in. If you have a choice go to "Charbroiled" Charlie company, nary a cold day, but we had 34 black flag days(and training don't stop)
airwinger