I’ve completed the software.
I abandoned the SOIC test clip in favor of wires soldered directly to the board. The SOIC test clip loses contact with the IC if you just look at it funny. It’s very irritating. In the future, all boards will have an in-system programming (ISP) connector.
I just need to finish the mechanical part. I’m waiting on an order for some more nylon screws because I screwed up and ordered the wrong length.