I had a mite problem that came with my snake from Petco.
I tried all the other mite sprays, etc. but (PAM) Provent-A-Mite is the best thing you can do.
It's about $18 or $20 a can, but you don't need much and it works.
I have a display tank, not a rack set up, but I took everything out of the tank. I baked all the wood in the oven at 250 for 30 minutes or so and soaked the hides, silk plants, etc in a very mild bleach solution in the bath tub.
I also washed the tank in a mild bleach solution.
(Be sure to soak in straight water and rinse well afterward)
I used a white newsprint for substrate that I changed every few days (could see the mites on the white).
The mites will hide in little cracks and crevices, so make sure you take everything into account (even the digital thermometers got sprayed)..
I would soak my snake in a lukewarm bath every few days. I used an infra red thermometer because what feels warm to us with a 98 degree body temp is actually way too hot for your snake (you can see the mites in the bottom of the bath water..gradually become fewer).
I would go through this routine of washing everything in the tank every week for about six weeks. I sprayed a little PAM on the tank and everything that went back into it each time.
I probably went way overboard, but it was all out war in my opinion...nasty little buggers.
Even to this day, I QT my substrate in a garbage bag. I'll spray PAM in the garbage bag, shake it all around and leave it there tied up until I need it.
I don't put anything new in my tank without being washed, baked or PAM'd now.