To me there is one question that comes to mind,
In the first point you mention adding a bar from the right side that pushes back the morale bar (if big enough).
From a player perspective i feel this can be confusing.
Up to now i've learned that one only needs to worry about unwanted soldier behavior (e.g. battlefield naps) if the secondary bar approaches the length of the main bar. Or any bar approaching zero.
This proposal would mean that an additional mechanic needs to be learned (check length of an additional bar from the other side and it's impact on the main bar).
Would it not be simpler to have the 'pain' bar behave like existing secondary bars and adjust calculations accordingly (for instance based on the difference between currentMorale and pain)?
As an additional note:
During years of play ignoring painkillers has become natural. I'm pretty sure this proposal will bite me in some way, but that is not something one can hold against this proposal