Get two identical hides. That way she doesn't have to sacrifice heat for the hide that she prefers. Plus, going through three different hides rather quickly is probably stressing her out more and driving her into the hide she is familiar with. If you haven't tried them already, I can highly recommend the ones from Reptile Basics (http://www.reptilebasics.com/hide-boxes).

Regarding what to set your thermostat too, I also have a hydrofarm and set mine to 92 using paper towel as substrate. It fluctuates +/-2, and 96 is way higher than I (and my snakes) are comfortable with.

Good luck with Lucy