You have a nice setup there! I used to keep my ball pythons in glass tanks but they hid all day long, it was like having a bunch of empty tanks around the room LOL. Ball pythons staying in their hide all the time is perfectly normal, it's one of the reasons you can keep them in tubs in a rack system, they prefer to be in a hidden spot most of the time.
Actually I don't think 87 F for the warm side is out of line. If you watch old videos of big breeders they used to crank up the hot side to 94 F, but after years of research they found that temps that high can make the males sterile temporarily. So they have been dropping the temps year after year. Most have dropped down to 88 F as the normal hot spot temp and that's what I use for all my tubs. At 87 F, just one degree under, you are just talking about the difference in the accuracy of the temp probes LOL. I do keep my ambient temps at 81 F - 82 F but 79 F should be OK too. 90 F for the hot spot should be fine. I never drop my temps for breeding season or any other reason, they seem to all breed fine and a drop in temp seems to just make a bunch of them go off of food.
