How to brumate when the house is too warm?

[paulh]

... The attached garage was also a thought but it's dark around the clock with no windows and it drops down into the 40's at night. ...

No windows is ideal. If the garage doesn't get below 40 degrees Fahrenheit, it sounds good to me. However, I worry about the place getting opened often to let a car in and out, which would not be good. Or you can try partitioning off a corner and insulating it.

I've used a refrigerator to brumate garter snakes at about 40 degrees Fahrenheit. No problems, but you do need to be careful that the snakes have plenty of water. Dehydration is the biggest problem.

Good luck.