I have not tried this myself personally, but unfortunately I think there might be some challenges with this approach. It's a good method for setting up a shareable filesystem, but the auth and roles files I think are inside of the data directory, and what those instructions are offering you is the ability to mount a single drive. Mounting the whole drive (and hence the data directory) wouldn't permit nodes to individually manage their data, I think there'd need to be some way to mount just a file.
Separate LDAP infrastructure wouldn't be necessary though. You could set up a shell script via cron on each node to simply take a copy of this data from whatever central location you'd prefer to specify.
