I insulated a glass tank AND ran a space heater in a cold room last winter and it was a constant fight. You'd better REALLY like your display setup to keep up with a setup like that.

IMHO, if you have to keep the enclosure in a cold room, you're best bet is too look into plastic caging like RBI, AP, Herpenclosures, etc, these cages retain heat and humidity better than glass many times over, otherwise, in the event of a power outage or anything like that, you are truly risking your snake's life in a setup like that.