dinomom
Chameleon Enthusiast
Because you have dry air a small personal fan filled with ice might help you get more of a drop at night. They work like a swamp cooler but only if you have dry enough air. Direct it into the cage but not directly where he sleeps. You can also place gel ice packs on top of the cage directly above the sleep spot each night to create a cooler spot there where it is most needed.
You can also try this. I found it is relatively useless with just water. But if you fill mostly with ice at night, as the ice melts into cold water through the night it should help a lot.