I found a bug in my code based on a misunderstanding of the Arduino Serial library. I rewrote my code to take that into account and it looks like WSJT-X 2.2.2 (with the newer Hamlib) is working. That's when I choose the FT857 setup. I still have an issue when I use the FT817 with rigctl-wsjtx that it doesn't seem to send any messages or commands to the radio.
73,
Mark, N8ME