The following is an insane train of thought… I am honestly re-thinking things that shouldn't be re-thought. It is entirely unnecessary for most people. Only fool around with this level of tweakery if you really love messing with things and you have time to burn.
I'm pretty happy with the modified version of the OLKB Planck layout that I've been using for a number of years. I use a separate finger on each column for each modifier, and it works really well. I'm having to modify this for my new Kyria keyboard… because I'm trying to make use of the thumb mods effectively.
While discussing keymaps, I've found it helpful to discuss these basics of what a keymap is, so that you can scope your changes to just one or two areas at a time.