I am looking to do something similar with my store. Did you ever find any sort of solution to this?
I am a software engineer so I have no problem writing code to modify Shopify, but I am new to the Shopify platform, so don’t know the ecosystem yet. I somewhat doubt that there is a way to do what we want with the available Shopify development tools available (editing themes with Liquid, custom metafields, etc), but thought I would check to see if you got any answers or any further information. You mentioned “can’t find a solution that is simple.” Does that mean you possibly found a potential solution that is not simple? Not simple might be Ok for me.
I have already modified my store extensively using metafields and custom Liquid templating code, but I have not discovered any way to modify the backend (i.e. database) of a Shopify store, so I am guessing that what we want to do is probably not possible on Shopify.