I got brave and switched to 9p with default settings. Wow - FAST. It does help with the time stamping issue that the "Clock skew detected" error represents, but I still get the git related error.
Running same container under Docker Desktop, and running the same "make clean all", I get neither error. Going to continue to poke at it - maybe the answer will become clear, but if anyone has ideas, I'm open to playing around a bit with this!