That's a fine setup as long as you can consistently and regularly monitor temps. I use CHEs on dimmers for carpet pythons, but I specifically want them to have changes in temperature with night drops, and seasonally as well. Various types of heat lamps play an important role in the history of chondro keeping techniques, and have had their successes.

If you feel that your ambient humidity a few hours after a mist is too low for your snake, your exo-terra is more than capable of handling a thick layer of substrate that can be kept moist (NOT wet, but similar to a good moisture content in garden soil). My geckos are in planted vivariums, and their substrate provides enough moisture content to keep their humidity a good 40% above room ambient.