Just like Virtualmin has a way to backup the Virtualmin machine and it's settings, Cloudmin needs a way to backup the Cloudmin master and it's settings. Near as I can tell, there's no built in way and I would need to painstakingly try and figure out where all the settings I need to keep are, etc if I ever needed to rebuild or restore the Cloudmin master. Not using replication, and, replication is not a backup anyway. This backup should not have anything to do with storing the virtual machines, just speaking of the Cloudmin machine itself. Then, like Virtualmin, it should also support restoring backup on a new machine, i.e., to move Cloudmin to another machine.
Not having any backup facility was a surprising omission. Unless I missed it!