I don't go out of my way to cool any enclosures, I keep my thermostats the same year round. The room temperature will get cooler during the winter obviously, I just make sure it doesn't get to cool in the room, otherwise, I will use a oil filled heater to maintain a temperature in the mid 70's.

I have done it this way since I started keeping ball pythons. Keep in mind, not all females will copulate when you would like them too. Occasionally, I will have a female that won't copulate as well.

Best of luck with the three females!