Hey,
I dive the IL, KY, and TN quarries all year and just got my first 7mm this past Christmas so I’ve also been a 5mm diver up until now. The water temps in the dead of winter will dip into the low to mid 40’s in some of the quarries so you’ll be fine based on the water temps you are used to already.
Hit me up when you get to Clarksville and I’ll be happy to hook up with you and show you the diving in the area.
Michael