Over illuminate the dark space before you descend.
Most of the nasties hate sunlight and will crawl away from a brightly lit zone if you give them enough time.
Heavy metal music can work against sensitive ears.
Scrap carpeting can be of great value: you can spray it with repellant -- take your pick -- and be placed face down. The under side then makes a nice slip and slide surface.
Mechanic's stick lights -- use more than one -- are effective in confined crawl spaces -- and robust enough to survive.
Heat guns are also very effective for driving insects away. Any snake that strikes will aim for the gun head in as much as their vision is in the infra-red.
Suck it up and belly down!
Cheers.
