Got in touch with a consultant and he recommended working directly with the files on disk, rather than through the database server.
Working that solution now, so THR’s web servers can’t connect to the database server and I’m not sure what message you’re seeing.
Either this will work, or I’ll restore from backup.
My fingers are crossed. Should have an update in the next half-hour.
(His estimation was that if it had already run 30 hours then it wasn’t going to complete, and I might as well take a faster approach to get things running. Here’s to hoping he was right.)