Agh. I had a screen lid on the bin that I would've sworn she couldn't push up, or even try to, but apparently she did. Where would a burrowing type snake hide?! I looked under everything, and I left a heating pad out underneath a shelf, hopefully she'll seek out the heat. My house is the most cluttered thing in the world, and it's got a huge, equally cluttered, basement.
She's not an aggressive feeder by any stretch, so I doubt I'll find her with rodents, and sand boas barely drink, so I won't find her by leaving water out either.