I think, if you have the tub's warm side at 88-95 then it usually should variate enough for the snake to thermo-regulate with no problem.
I don't have a ton of experience with this, but I would assume if they get too hot, they move to the cold side for a bit and can move back to the warm side if they need to. I don't think it is majorly bad if the temperatures on the cold side arn't perfect, as long as you have regular warm side temps.