Yes I am measuring the temp of the basking spot from inside the enclosure right above the UTH. And yes, I bought a UTH with a thermostat built in. I have read that the UTH should cover about 1/3 of the bottom of the enclosure. That is what I have done.

I just moved him back to his smaller enclosure.

So how should I tackle the ambient heat problem? The enclosure measures 31”x 15” x 7” or 12 gallons (according to the online calculator I used) would a CHE suffice? Also last time we measured him he was about 22 inches long and 181 grams.