Just wanted to post a positive update! After one more reptile spray treatment, I continued with PAM-treated paper towels as the substrate, and Ravus has been, by all appearances, mite-free for coming up on a full month now. His appetite has not been affected at all, as he's a voracious eater, and he's been gaining weight steadily and just had his first shed with me, which went fairly smoothly. Also, there was no spread to my other snake Iggy, so he's in the clear!