@ Capricorny

Thanks for your comments. In answer to same:
1..Yes, that is the intention.
2. That's a neat idea in itself. Right around line 738 of init of minirt.gz, to be specific
...is the operative area of the code. But, won't that require a re-mastering?
3..Not sure what your concern is here. Tarring /KNOPPIX was my crude idea of how to proceed.
...A more elegant approach would use knoppix-data.img, but I wasn't clear on just what .img
...means. I expect it has to do with loops. Tar is simple and available. Most of the time
...is spent in gzipping, not tarring.
4a.I keep a belt-and-suspenders copy of the update on another usb. What I feel is unique here
...is keeping a self-contained backup. Being able to do this on a 2 Gb set-up surprised me.
...Both the update and the persistent stores on my set-up are only half-full after six months
...of tweaking.
4b.The reason I decided I need a backup, is some of my tweakings result in a LiveUSB that's
...not Live anymore. Of course if it isn't dead, it should serve the purpose as well. If not
...you need a working Linux to make the repair. In my case I just use the old LiveCD.
5..Anybody's choice here; could be in /home, just as well.

__________________________________________________ ___________________________________________

I probably should have prefaced my example with the thought that by 'proof of principle' that
it's the idea that counts, not the specific implementation of the example. Having struggled
to read even parts of Knoppix's minirt.gz, I know there are lots of other ways to do things,
than I had ever run across before.