InformationDino, aka @topgundcp has created a written tutorial on how to do this: Solved FYI: Setup Macrium Rescue to boot from an Internal/External USB HD/SSD - Windows 10 Forums
Also a video:
Dino did it a completely different way than I did Cliff. I used Mini Tool to make the 2GB partition, then copied all the files to it from my usb stick, then removed the drive letter. Done.
So not sure now what the difference is between these 2 methods. Except the way Dino does it, MR has a assigned drive letter, mine does not.
I removed the drive letter also. I'm not sure it makes a difference though. It works either way.
The only difference I would think is, you are not bothered with it in File Explorer with out the drive letter, but it will still show the partition in Disk Management. Maybe with it showing up in File Explorer it's easier to update it, as you'll be able to access it online.
Kari replied to me in a post elsewhere with useful information. https://www.tenforums.com/general-sup...nu-option.html
It seems the boot option will work fine so long as I keep the recovery drive up to date.
Thanks for your help.