Hi Friedrich, not a solution but an option: Try building your own ArchISO. More below.
> As there is space left on the medium I created one more partition to load or > save stuff from the system booted. I had a similar situation where I wanted `Borg` (my backup executable) and some `pass` encrypted passwords on my recovery disk. I ended up building my own ISO. Which was a nice winter weekend evening project and a lot easier than I thought. Here’s the wiki page: https://wiki.archlinux.org/index.php/Archiso —Florian
