I saw your podcast so I had to listen. Very nice. I actually pretty much followed along in spite of never having used tmux.

I have a similar project using abcde to create 4 audio cds at once. (or even 8) I have two xubuntu systems with 4 optical writers in each. (you have to have a tower)

I have my cds in folders with the numbered audio tracks.

Then I have a shell script to start abcde 4 times, once for each device. Before you know it I have 4 more cds to test. Reload blanks, hit up arrow, and go again.

I don't use it much anymore now that cds have gone out of fashion but it was a cool project that used to save me a lot of time.