I'm not speaking from personal experience, just regurgitating what I've read, but since it has been about 12 hours since you updated and no one replied yet...

Provent a Mite (often abbreviated as PAM) seems to be the only product that actually gets rid of mites in a single treatment. Other products may say that they do, but based on the experiences of people on this forum, it doesn't appear that those products work as claimed. The key may be that it says it kills the eggs "on contact" but what about the eggs under the edge of a scale? Or down in a crack in one of the cage decorations? Just speculating...

So your best bet is to buy a can of that stuff. I think it has to be ordered online.

While you are waiting for it to arrive, the reptile relief is apparently effective in killing the live adult mites, so it will at least reduce your snake's discomfort.

Most people recommend going with white paper towels as a substrate while you are treating for mites so you can see the (hopefully dead/dying) mites.

For hides and other stuff in your enclosure, if it is non-porous you can soak in a bleach solution and rinse thoroughly. Things like driftwood can be baked for a long time at a low temperature (recommendations vary but I think the minimum I've seen was 1/2 hr at 200 degrees, I'd probably go a little longer or a little hotter to be sure). If you have something like an aspen substrate, you probably kill the mites by baking it, but since it is something you are supposed to change periodically anyway, you could just throw it out and start with fresh once you are sure the mites are eradicated. The reptile carpet thing can probably be soaked in bleach and then rinsed very thoroughly.

I have no idea about that powder. Is it intended for use with snakes? If so, it probably won't hurt your BP, but unfortunately the pet supplies industry isn't very well regulated so there are a large number of products that are either totally ineffective or unnecessary, and at least a few that can be harmful.