Thank you to everyone for their advice.
Some notes for clarification.
1. It's an Exo-Terra tank, so the framework does leave space under the glass for airflow.I just connected my 100W Exo-Terra thermostat but I think I might have to return it. The plug connector that the heat mat plugs into is very loose, so I'm not sure if it's making a connection. I set it for 92, so I guess I just have to wait until it cools down to see if it's working properly. I did place the probe between the mat and the glass under the tank - hopefully peeling the mat didn't damage it or the adhesive.
2. I checked out the Focus Cubed replacement tops. They look fantastic, but it'll have to be a purchase for a couple of months down the road. For the short term, I'll be using plexiglass. It definitely looks like the screen is the issue regarding humidity. For the short term until a more permanent top is ready, I took a thicker blanket and folded it for extra thickness, and have covered about 60% of the screen. The humidity has gone up and seems to be holding around 64-65%.
3. I will be buying a second thermostat for the hot side CHE. I'll hold off on the cold side one until I get the laser thermometer and can check the surface temps better.
4. I've already removed the skull hide and placed the coconut in its place temporarily. I'll be getting another rock cave for the cold side. Since the heat mat was turned down, she has gone back into the cave. She seemed to like it before, just didn't stay in it long, so I think the comments suggesting it was too hot were valid. When the moss arrives, it'll hopefully make for a good humid spot for her. If that doesn't work, I'll go with the plastic tub idea.
5. I'm going to look into the DHP bulbs for sure. If it means I replace the CHE's, whatever, if it's better for her. I can just keep the CHE's as emergency backups in case the other burns out and I don't have another on hand.
Thanks again for everyone's help! I think I'm mostly set, just some fine tuning until I get it perfect. Much appreciated.
Ian