Here are a couple of pictures of the whole enclosure. The snake actually did move into the bigger warm side hide last night, so it seems that she is indeed not stupid. If there are other ways to optimize the enclosure though, I'm happy to hear them.
Ambient temp is 81-82 on warm side, 79-80 on cool side / very near walls. Surface temp is 77 on cool side, 88-89 on warm side at the plastic. I could turn the heat pad thermostat up another degree to hit 90 inside, but it seems to overshoot and get slightly too warm. The overhead lamp thing is a ceramic heat emitter.
Humidity can be a little tricky to stabilize since the enclosure's volume is small relative to the lid/substrate surface area, so it's easy to overshoot when mixing in water. It's pretty stable once it gets going though, and I might add a bit more substrate to help with this.