Hmmmmm.
A few questions:
1. Can she fit comfortably and snuggly in both hides?
2. When you take ground temps on the hot and cool side, are you lifting the hide to get the temp in the hide?
3. How often are you checking temps with the temp gun? Could it be hotter during the day?
4. How often are you feeding her a medium rat?
It sounds to me like temps or humidity are off (although what you say sounds okay, although 75% is a little high for a BP not in shed) or she's hungry.
The only other thought I had is about the cleaning of the tank. When you clean the whole tank, does that include fresh substrate?
Any clarity you can give on the above would be helpful, but I too am not sure what's going on.
Are you giving her a day/night cycle? 12 hours day/12 hours night/dark?
As you seem to know, BP's often come out and roam at night, but not during the day so much.
Good luck and keep us in the loop.