While writing a reply to this topic: viewtopic.php?p=90710#p90710 I started thinking about how a script could easily create a new read-only numbered upper_changes to use on the next boot.
If it's easy enough to copy the current upper_changes to a numbered layer while running the system, a script would have to probe and perhaps ask the user about naming and numbering it. Once copied it wouldn't be mounted until next boot, so shouldn't be a problem sitting in the system directory until then.
But what about deleting (or renaming) the currently used upper_changes before rebooting. Seems to me that would have to be implemented in the shutdown procedure, or the boot script. Is it possible in the w_init to look for a marker file (or other log) indicating that the upper_changes directory had been backed-up/renamed for the next boot, and upon finding that log entry, rename or delete the working un-numbered upper_changes before loading the new read-only layer and creating a fresh upper_changes?