In what way would an SEC team not be "properly equipped to play up North in December"? Like, is the thought that they won't have the budgets to rent heaters and buy long sleeves and hand warmers? And would the weather only impact one team? Has our team been playing all season in shockingly cold weather so that we're well experienced to playing in the cold? Not to mention that SEC teams have plenty of guys from the North on their rosters, just as Northern teams have plenty of guys from the south.
Year after year, people make a big deal about cold weather teams coming north late in the NFL season...and it's pretty much neutral from a spread standpoint.