Removing default values / total conversion mods

I would like to create mods where some or all of the default policies / party names / etc are removed; right now, I think the only way to do so is total conversion, changing the main data folder as opposed to just adding things into its own packaged folder.

Can we get an option to do something similar from a mod? This would allow us to enable and disable it via the game interface, and keep the other missions working, instead of having to change the whole game for this purpose. Maybe allow to remove specific policies on a mod, and/or create a flag that means “ignore all the default values of this type for this mission”; this would greatly help.