I think you will be fine. The next time he/she sheds you can provide a humid hide like mentioned above or use plexiglass to cover the top 2/3's of the tank. Get the measurements of the mesh portion of the screen top and either Home Depot or Lowe's will cut it to fit.
What I had to do to help with my humidity issues during the winter is change substrates. I went from outdoor carpet to cypress mulch. That has helped a ton! I still need to spray the inside of the enclosure every so often. In 3 weeks I hope my humidity and ambient temp issues will be a thing of the past because I'm getting two 2x3 enclosures from Reptile Basics!!!