Whatever you do, do not put them into the same room as your reptiles! Putting them in the same rack is already cross contaminating. The mites can and will travel up the rack as does other airborne illnesses.
Always quarantine in a separate space.
Is there anyway to have the rescues in a stand alone tub in a different room? Or as mentioned, in a different house?
For mites. Since they are infested, bathe the snakes in warm water with a few drops of Dawn Dish Soap. Rub the snakes down to get the excess mites off. Leave the snakes in the water for 15 minutes. Don't fill the water more than half way up their bodies so they don't drown themselves.
Get Provent-a-Mite (PAM) and treat their enclosure. Then use the bare minimum set up: paper towel substrate, water bowl, and hide.
PAM will usually take care of the mites on it's own, but you can bathe the snakes with dish soap every other day or so.
If you don't have PAM, you can get NIX lice treatment from your local pharmacy.
While you're at it, I would personally treat the rest of your collection as a preventative too. And whatever you do, do not handle those snakes before handling yours. If you handle the rescues, change your clothes and take a shower afterwards.