I've mapped backspace and control-backspace behaviour (backspace a word) to a thumbkey, which I think is a better option than capslock. Most keyboards don't have good thumbkeys though, so I'd recommend keeping whichever you use more on backspace. You could also make a capslock layer with all of them with binds like this (arbitrary letters):
caps+a = paste
caps+r = copy
caps+s = cut
caps on release = backspace (example implementation for ahk)

You could also add whatever other stuff you want to that layer. I personally use y, p, and d for copy, paste, and cut.

Hmm, interesting, hadn't considered dual-role modifiers. I also like the idea of having a backspace-word shortcut.

@DreymaR I am using your tarmak1 PKL script, I noticed some caps-lock extend stuff in the config, but I disabled it as I wasn't sure what it did and it conflicted with my existing AHK script :-P

OK I get it now. I especially like the idea of having navigation keys within easy access. Once I've completed my transition to Colemak, I'll look at this capslock-extend idea in more detail.  Would this script still work in combination with the "official" installed Colemak layout (in Windows)?

You probably are already aware of this, I imagine it's country-dependent, but to get your PKL layouts (including the Tarmak ones) to work correctly for me, I needed to comment out all OEM lines. Otherwise various symbol keys would get incorrectly remapped.

My Caps Lock is Alt. This is a result of me using a MacBook Pro, whose Alt button positions are a strain on the fingers. It works great for me :)

Additionally, I've realized that I never combine my home row buttons with Alt, and that some of the characters that I use when programming are normally quite far from home row. Therefore, Alt+uhjklæøpo is now /{()}[]!$, respectively. Alt+Shift+u is \. (I use QWERTY right now, going back to Colemak soon, will give the same buttons the same Alt mappings : )

Yes, GitHub. I'm getting around to that, soon, I promise. :)