I have so many common one-liners I use in my current project (that I access using fuzzy search via ctr-R) that I'm thinking about having a file a'la "my-commands" and have it appended to my history, somehow.

That would truly be the opposite of this advice.

Maybe I need to think about this a bit more :)

Greenclips [1] works well for this if you're a rofi [2] user. You can set a staticHistoryPath that points to a file. When activating Greenclips, you can search for the desired command. I've been using this on my Linux box for the last year or so and haven't looked back.

[1] https://github.com/erebe/greenclip

[2] https://github.com/davatorium/rofi