Huh, I had not noticed aspen messing with the humidity in my boa's cage, though I do use paper even the cages that my female balls are in. Anyway, I LOVE what you've done with the tank! It looks great!! I have 2 suggestions that you might want to consider: move the temp gauge down so that it reads the temp at snake level, and cover three sides of the cage to help with security issues. I love the short little branches and the hides are great! Yea roommate!!
Ooops, one more thing...Where is your snake??? We need pictures!!!