So even if the room is cool wich is completely unatural for boas and you only heat the bottom of cage that is okay?

Would think they need warm air.
I used to see 3 ft smallish size boas all the time and hotter the night the more you would see.
Coldest I recall in a yr was 70 degrees one night and that was cold night.

Kingsnakes I can see UTH but boas come from tropical places.