I actually don't use a substrate* that adds humidity, but you can if you want. And I'd set the UTH to be not over 86*. If it's too warm, they won't use it at all, when they really should. My 3 "hatchlings" do have humid hides btw, since tiny snakes are much harder to help shed if they have any problems, & they clearly enjoy the moist moss mix. In lieu of humid hides, you can mist instead, especially when they're about to shed.
(*I use a mixture of clean paper shreds & some Carefresh for texture & weight.)