You guys are awesome. Lots of really good brainstorming here, thank you! The switch in question does appear to be a LEFOO LF10, with an unloader. I say 'appears to be' because it is supplied by Eastwood (the auto tool company) as a replacement for the original pressure switch on their 30/60 scroll compressor. It still has the Lefoo logo on it and appears identical to the standard Lefoo switch, though I don't know for sure it's identical to the off the shelf version. But for purposes of this project, it's the same.
I love the low-tech pulleys and strings idea, but the compressor is out behind the garage, so would require drilling holes in the wall etc., which I'd rather not do. I've thought about a hard-wired safety switch or relay etc., but I'm not sure it that would be good for the machine if I cut the power everyday (and don't want to attract attention of the building inspector.) It was actually a power outage that killed the original pressure switch.
So, I've picked up a door lock actuator 'kit' that comes with a controller and remote controls. I had planned to make a wireless arduino set up, but this $25 Amazon kit covers virtually all of the electronics (other than power source). I'm thinking I'll design and 3D-print some mounting and actuating mechanism. Stay tuned, and thanks again for all the great ideas!