What are you using ON him?? In my opinion, Reptile Spray from Reptile Basics is the only safe mite treatment to put directly on your snake. If that is what you're using, then it should be fine. But if not, stop!!

The Reptile Spray shouldn't bother that cut. I remember your post about that. I am not 100% convinced that that is a cut at all. Some snakes have a "split" in their ventral scales, but its not an actual wound. Either way though, the spray shouldn't irritate that unduly.

If he doesn't like being sprayed (and most do not), just place him in a spare tub, or your bathtub, and lightly spray him. Let him crawl around and calm down before you pick him back up. Perhaps someone else can watch him while you take care of his enclosure....

I personally use the Reptile Spray on enclosures as well, but you can use Provent A Mite (PAM) so long as you follow the directions VERY carefully and allow it to dry COMPLETELY before you put your snake back.

If that is in fact an actual cut on your snake's belly, I would be keeping him on paper towels until that fully heals. Gut the enclosure and wipe it down with the mite spray completely, being sure to get in every single nook and cranny both inside and out. Do not rinse, allow to dry completely. Get rid of any natural wood branches or bake it in the oven at 350 for 20min to kill anything in the wood. Run hide boxes and/or water bowls through the dishwasher. Replace paper towels with fresh. You may have to repeat this in 2-4 weeks. And I would treat EVERY enclosure for mites in the same manner whether the other snakes have mites or not. If they don't yet, they will. Mites travel.

This should work with diligence and patience. Mites are a pain in the rear, but not impossible. Good luck!