Good news!
A CO-V50 surfaced in Guam for the low price of $8.50 CDN, plus shipping (which was not that bad, suprisingly) -
https://www.ebay.ca/itm/323348617061
This is the Japanese version of the Autochanger Commander and supports two autochangers. There is good reason to believe it will support the North American unit at the protocol level which is what I'm ultimately after.
It should arrive in a few weeks.