This is not always an option, like you say it depends on the cooperation of the base config files (having the include and in the right place) and the tools used

This is not always an option, like you say it depends on the cooperation of the base config files (having the include and in the right place) and the tools used. It won't work foor all cases either. I just want to have the ability to make modifications and sign or bless them somehow with a system admin key. Root is not enough, for understanable reasons. What is possible is to modify offline (through recovery) and then 'bless' my changes. But this reverts after every reboot. There should be a toolchain where I can make legitimate modifications in a secure manner to system files. Like every other OS has. There should be some kind of user key to sign modifications with. Apple has just ignored this whole toolchain and replaced it with a "just trust us" blanket.