In my opinion that is FAR TOO COLD to be cooling gila monsters and you will wind up with a dead gila. Mark and some of the others who have been breeding them much longer than me will probably attest to this. You really shouldn't expose gilas to temps below the mid to upper 50's for any prolonged period of time. I will actually allow my gilas to bask for short periods of time during the cooling process and they will have some levels of activity such as drinking water. For those gilas who are not being bred, they are kept on a regular "summertime" schedule.
Rob Carmichael, Curator
The Wildlife Discovery Center
Lake Forest, IL