All cornsnake and kingsnake books/care sheets seem to specify fairly high ambient temps. That surprises me. Those aren't the temps those North American snakes are going to find much of the time in nature. Maybe the wild ones spend a lot of time uncomfortably cold, and suffer for it. I really don't know.
My kingsnakes are from this actual area, and it is not all that warm most of the year. I posted finding fresh road kill Pittuophis earlier this fall - well after the weather had turned cold. What were they doing out?
I understand the need for a digesting hot spot with a useful hide - no argument there, and based on the books, I have made the tanks warmer than our room temps, but frankly, I question the necessity of doing it.