Honestly, what you want to do is easy... the problem is, your experience level.
Agreed Also, I don't want to make partitions per se. I just understood that to be the advice above. If everything can be done on the entire disk with just one partition, fine by me.
in your case I'd just use the root share plugin and keep backups of your docker folder or any other folder you have on your root drive.
I'm afraid my experience level is not high enough to understand what you mean with 'the root share plugin'... 😬
But i do agree, a flash drive is a far better solution than any of the above (assuming you have at least USB 3.0)
I'll see if I find a USB flash drive lying around, but if the entire 160 GB SSD was to be dedicated to OMV and Docker, how big should that USB flash drive be...? (I also don't think I have one...)