Turns out he's (she's?) just an occasional visitor. They "den" from place to place, so he (she?) just shows up once in a while to check for mice...and spend the night. I'm not sure I could find all the possible entries; they're such great climbers. Their rear ankles rotate 180* for fast, safe rappelling. They can "stem" up cracks and fissures (pressing against opposite walls simultaneously).
They're ancient mammals, going back to the Miocene over 20million years ago. Their ancestors probablv preyed on ours.
I could try to trap it with dogfood (if I had any). But I'd just as soon have it around rather than mice, rats, chipmunks and scorpions. Especially as Ringtails are not common around here.
Having my own "miner's cat" is kind of special.