I am pretty sure the ThumbDV I am using is of the second generation, so it doesn't need to be forced to the 460800 baud rate. I had forgot about that requirement for some people, but as you said, it can also be done from the command line.
At the moment I don't have anything running on the Pi/ThumbDV board, but AMBEserver. It is now a custom version, since I added the code to have it write out status to the syslog file, but I never got around to writing a sys.d file since I was starting and stopping custom versions all the time.
I personally use Buster to connect to reflectors with the setup. (I'm primarily a Mac/Linux person)