It's not really necessary to lower the temps. Just pair established animals in good, proper condition. If you don't lower the temperatures, you don't have to worry about low temperatures negatively affecting anybody.

(As a for-instance just how little temps seem to matter, my temps are actually the most constant in winter with my current setup, as winter and early spring are the only times I run a heater in the studio/snake room, at a steady 72-73ish. In summer, without climate control beyond window technology, I can see swings from the low 80s to the low 60s in this same room. I choose to breed in winter, and my BPs tend to ovulate in late spring and lay in early summer.)