Well the uth works better on the bottom.

Reason being they like belly heat. Ara said get a bigger light. That i wouldnt do. Lights suck out humidity like crazy. If you was using a 10G tank u could put the zoomed on the bottom and used the feet to raise it off the ground or bottle caps (i use caps cuz they are higher).

Also you uth may read 84 now my uth has reached 120* not hooked up to a tstat. And yes there was NO snake in there at the time.

Your best bet would of been to just mount the uth on the bottom cover the time with foil or a damn cloth. The aspen holds humidity fairly well.