Keyboard Shortcuts for XF86 things and/or remapping function keys - possible?

Howdy Folks.
I've messed around with this idea for a few hours, loads of searching & reading - tried getting xmodmap to work (failed), of course tried mate-keybinding-properties (which doesn't recognize XF86Paste or XF86copy as valid commands) I even tried Autokey, which mostly just barfed alot & had to be force closed on my U/M 18.04.5 PC.

Single key mapped to each of XF86Paste & XF86copy functions which I use quite a bit.
My immediate thought was making a couple of never-used F keys do those, but thus far I have failed rather soundly.

I will hugely appreciate if someone will be kind enough to guide me in a working method to get this done (if even possible), please ??


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