Thank you for your advice. I do hope changing the hides is at least a step in the right direction. Yes, I've taken the temp on the inside surface of the hide a few times. When it had the help of the California summer heat (ambient temps easily staying at 80 F), it did okay at around 86-87 F, but now that the nights are cooling off, it's closer to 85 F, which was what prompted me to dial up the Herpstat setting a bit. However, I was also hesitant to turn it up too much, since Iggy is strong enough now to sometimes nudge the hide out of place while he's roaming around outside it. I'll probably try turning up the space heater to bump up the ambient temp to 80 F as well. If my sister feels the room is getting a bit too warm for her crested gecko, we could relocate his tank if necessary.