Mites :(

I'll chime in with my endorsement of bcr229's above write-up, as I referenced it a lot when treating my second BP for mites (luckily detected very early), and was able to successfully eradicate them. I specifically used the Provent-A-Mite for the enclosure and the Natural Chemistry spray to wipe down the snake itself.

Update... so far since treatment I have seen no evidence of any mites.
She’s still in quarantine conditions of course.

No eating issues.

I have noticed some neck wrinkles over the last few days... I am worried she is dehydrated? But maybe she’s going to go into shed. Maybe they shed after a mite issue to heal? That would be an encouraging sign.

Anyway hopefully all good so far!