I'm assuming this is because of the lamp above the warm side...
Aim for keeping the surface underneath the hide at around 88. The temperature on top of the hide is not as important, but it should not exceed 92. When it comes to raising ambient temperatures, you may have more luck using just the UTH on the warm side for the basking spot and using the lamp(s) on the cool side to bump the ambient. But it's really a matter of experimentation.
75 is sufficient, but 80 is fine. And during the night 70 is perfectly fine, as long as the warm side stays in the high 80's.