Thanks for the input and the note about using a temp gun, I had been using two digital thermometers to measure ambient temps and hadn't tried using the temp gun yet!
The temp gun showed that the surface temperatures were higher than what the digital thermometers were showing so I lowered the temperature. I was able to get the gradient to 80-87F for surface temps measured with IR gun, and 78-84F ambient temps measured with digital thermometers.