They sell PAM (provent a mite) on amazon?
I've always had to buy it direct from pro products.
I wouldn't worry about spraying the floor or anything, just spray the affected enclosure inside and outside in a well ventilated area and let it completely dry.
Good luck, they are annoying but you found it fast and they should be eradicated quickly. One treatment is all it's ever taken for me (the very few times I brought in a new snake in QT that had mites).
oh and here is a write up about the life cycle of snake mite:
http://vpi.com/publications/the_life...of_snake_mites