I don’t have a GitHub account right now, but I might end up registering for one.
As for what I’ve found with the client (Windows client at least), is that I can run the installer with a minimal ClientSettings.cfg to enable Automatic Relay Select:
__RelaySelect_Automatic=1
When the BES Client setup.exe installs, the client initially fails to register (trying only the BES Root Server). But if I copy a working Relays.dat to __BESData\actionsite and restart the BES Client service, it does use the Relays.dat and performs an automatic relay select, finds a relay, and registers successfully!
So I think I can use that process for now; it still requires using a wrapper script to handle dropping the Relays.dat and restarting the BES client, but that’s considerably less complex than what I’m doing now (using wget.exe to hit every relay in a list and building a specific clientsettings.cfg based on which relay responds first).