Emacs and Windows manager keyboard shortcuts without Windows key

I found a classic M-Series keyboard and I want to use it. However, it does not have a Windows key (AKA Super key); only Shift, Ctrl and Alt. My keyboard shortcuts are cluttered as-is, since I try to control both Emacs and the Windows manager (Gnome) entirely from the keyboard. I rely on the Super key to identify Windows manager shortcuts.

How can I perform keyboard-centric work without the Super key?

On my Model M, I turned my Caps Lock key into a Ctrl key (this is great for avoiding "Emacs pinky"), then turned my left Ctrl key into a Super or "Windows" key. I use Caps Lock very seldomly, so I just have it bound to a key combination.