I'll be ready to upgrade the enclosure when the time comes. In the meantime I want to replace the paper in this enclosure with better looking fake foliage, but I consider it low priority and haven't gotten around to it. I have a nearly unlimited supply of used notebook paper, so it's easier to just keep replacing that for now.
I'm regulating the CHE using a thermostat with a probe suction-cupped to the warm side short wall, and the heat mat using a thermostat with a probe between the mat and the bottom of the plastic. This setup seems to keep the temps within 1-2 degrees fahrenheit of target values when the room varies by 5 degrees either way. The ambient temps rise when the room temperature increases, so I hoped putting the CHE probe very close to the wall (which should have its temperature affected more by the room than the middle of the enclosure) would mitigate this, but I think putting the probe in a hide or something might also be effective.
My only issue with the heating is that the surface temp of the plastic beneath the hides is 88, but ticking the thermostat up a degree brings it to like 93. I figure 88 is fine even with some variance and preferable to potentially getting too warm by sitting around 93, but it annoys me that I can't bring it to 89 or 90. I have a spare thermostat, so I might try making some sort of "and" gate to improve it.