You are welcome.

Ground temperature is 95% of the battle. You want the middle of the tank to average between 80-84F. Ambient might be the wrong word. The key is that there is a gradient. So if the hot side is 86-90F and the middle is 80-84F and the cool side is 78-80F, your BP can always find a comfortable spot whether he/she needs to digest or just wants to chill out (literally and figuratively).

Your BP will burrow if needed. If it's 90F on the heat pad where it meets the bottom of the tank, that's fine. If it's 85F above the substrate, for example, he/she will burrow to get to the warmer temps if he/she needs. It should not be above 90F anywhere your BP can reach.

Finally, I am not sure what an Inkbird is, but I am going to assume that it's a thermostat, is that correct?

If all you have is a UTH for heat, how are you keeping the cool side and middle of the tank heated?