The good news is I finished the Music-Optimized Breakout Board I started at Framingham Makerspace last Wednesday. All I had to do was add two headers, a diode, regulator and crystal to each of the 3 boards.
Then I was able to test-boot each one. All three came up the first time! I haven't run further diags yet, but it's worth soldering on the rest of the headers so I can do so.