Leo's do great at 88-89 so do ball pythons. I have owned Leo's for many years with those temps and also currently breeding Leo's. 85 is ok for a night drop for Leo's but not for daytime. I run my Leo rack at 90.5 giving me temp of 88.2 in tubs 24/7 and have big healthy geckos. But since your using aspen for bp you won't have the right temp for the Leo's unless raising them helped. Leo's IMHO should not be kept on anything other than paper towels or tile since impaction is a very common problem in all life stages, they simply can't handle it most of the time. Like said above you need a thermometer with probe or temp gun to test temps and more than one to test against each other. If you go the thermometer route get an acurite probed model 00891 they are the most accurate thermometer I have come across. The reason you can't feel for heat is bc are body temp is higher than heat requirements. You also should be testing temps at the bottom of the tub do to burrowing.
What do you use for heating? Heat cable, heat tape, maybe heat panels? I'm using heat cable and I placed my probe exo terra thermometer on the hot spot and it's only reading 85.3.