If you want to keep enough snakes that you need a rack then you shouldn't be keeping your room temperature in the 60s. If you like your house that cool it's fine, but the average household temp is in fact around the 75 range. The further the ambient temp gets from this normal range which the devices are tested at, the less reliable they become. Especially when using something non-proportional like a Ranco. Simply put, the easiest way to solve your problem is not with a bunch of modifications, but to toss in a space heater or up your temps. Ambient temp matters much more than many people believe when it comes to establishing a stable herp enclosure.

I believe if a poll of herpers were done, the average temp, atleast in the snake rooms, would be around 80. I keep my living room (where kitty is) at a constant 80-84, bedroom cooler because we keep the windows open, and our computer room even cooler than that. The first thing I asked we moved was what the average temp was year round, I got a "nice in the summer, but way too hot in the winter - like almost 30" from the previous tenant - which is about 80 or so. Why? Because we don't have precision control over our temp (we have an individual fireplace if we want more heat), and I know that this is the ideal condition for my snake and fish etc, if my heater were to blow they would still be fine without - although I do have a backup.