I’m not sure if you can show/hide like that, but as a workaround you can toggle auto-hiding with a qdbus command, and set a keyboard shortcut to run that.
Don’t miss this entire genre: classic LucasArts point-and-click adventure games! Sam & Max Hit the Road, Full Throttle and Monkey Island are a few of the stand-outs for me, and they all run on Linux via the amazing ScummVM.
Skipping the OS backup is reasonable, but you probably want to at least save a package list. Add something like dpkg -l > ~/packages.txt to your backup script.