This is my first BP and first snake since I was a child. I just received my normal female, Sheba, yesterday and she only stays on the cool side of her 6 quart baby tub. I have 2 hides in there (cool side, hot side). Hot side is around 90F and the cool side is 74F. I’m leaving her alone to settle in and hope she knows to go where she needs to go. Also my humidity is too high at 84%. I have a small water bowl and coco fiber substrate (which is dry to the touch). If the humidity doesn’t start going down I will remove the substrate and just use paper towel for now. I don’t really want to start messing with things until she eats for me. The breeder thinks she should be able to eat on her usual schedule Friday since she is such a good eater. Sorry this is so long.
I would say from that information you’re doing just fine, with regards to the humidity( but you know that). I personally use paper towel for all my new snakes just to monitor them easier.
The humidity could be high depending on where you live, otherwise just try to drop it a little and she should be fine. Some of mine used to sit on the cool side for days, so I wouldn’t worry to much. You seem to have a good idea on husbandry so she’ll be ok. I wouldn’t worry just yet. Let her settle in with no handling and she’ll be good.
I agree with @mnroyals, i always put my new arrivals on paper towels. It makes it much easier to see if there is a possible issue with mites and allows to check the bowel movements. I am sure sheba is just adjust to her new envoiroment and wouldn’t worry to much about her staying on the cool side. Congrats on your new baby and welcome to the community. 
Is your temperature reading device accurate? I dont know your setup but adding more ventilation would lower humidity maybe add a few holes in the tub. Other then maybe false reading for temperature on hot side she probably just preferred the cold side to suit her needs.
I wish I had used paper towel before I put her in there. Unless its critical I don’t want to mess with her yet. In a couple days I’ll change to paper towel if humidity is still high. My temps should be good since my thermostat and thermometer usually read the same.
Range is too high. 15/16 degrees of temp range is not copacetic with this species and tightening it up will help you avoid a lot of pitfalls… not sure the challenges you have to tighten up the range but cool at 78 hot side at 88 would be much better… honestly I find a lot more success at even tighter range tolerances