I thought you might have it but that doesn't work either. bandplan_dxcc291_user.xml does work but only when bandplan_dxcc291.xml is either gone or renamed.
I also discovered an error in my original solution. I am running "split" in WSJT-X so the dial frequency can go below 5,357 Khz to as low as 5,355.5 Khz if the transmitted audio is less than 500 Hz. The rig still transmits and the QSO is logged but you see this Out Of Band warning:
This is fixed by changing the lower band edge to 5,355.495 Khz.
This comes about because in the main UI, Dial Frequency is being checked against the bandplan whereas in the log, Dial Frequency + transmitted audio is checked against the bandplan. It looks like I'm defining a band from 5,355.5 Khz to 5,359.8 Khz but not really. It is still 2.8 Khz starting at 5,357 Khz.
I looked at the log in Log4OM hoping it would show which bandplan document is being loaded at startup, but it does not.