With your low temperature it could be difficult to keep a snake warm. If I was going to keep my room that cold I would do a few things... get a PVC cage like from Animal Plastics. Then I would put foam insulation on all sides but the front.

I would use a radiant heat panel on a thermostat to maintain ambient temperature in the low 80s. And use an under tank heater on a thermostat to maintain the hot spot.