I use an accurite digital thermometer...just had the probe over toward the back of the cage away from the RHP/warm spot, maybe 6" off the ground- it read 79F.

I feel comfortable with the accuracy of the readings I'm getting. It feels warm inside the cage, and even warmer under the RHP, and the thermometers says it's warm inside the enclosure away from where the RHP could actually directly heat something. The two snakes housed within the t8 are eating/doing fine. Finally, it's been chilly in my bedroom!! I love sleeping in a cold bedroom...upper 50's to low 60's is perfect!

It's too late tonight, but either tomorrow or over the weekend, I'll take some pictures of the enclosure and we'll see if things can become clearer.