First, I commend you on being a good father! So many have no problem turning their kids into game pieces. So well done.
On the halfway point thing, I think sometimes we LBSs put the emphasis on the wrong thing. if driving an extra 1/2 hour even things out, then do it. There is nothing wrong with being reasonable and accommodating. In fact, that kind of thing can go a long way in making your sitch a little easier to deal with. Look at it i reverse, what if you were driving 1.5 hours and she was driving 45 minutes? That would likely stick in your crawl. So try to be even with things. Accommodate where it makes sense. Error on the side of trying to show a conciliatory attitude. This doesn't mean you become a doormat, but reasonable accommodation doesn't turn you into that.
I detect one of the 180s you could do is like the above. You said: "I don't think I could have had that interaction face to face with her without it turning sour (I would have been pretty stony, as I have been more often with W since she moved out)." So 180 on that. Remain upbeat, friendly, accommodating even in person. Don't let it turn sour and don't return in kind. If she does start getting disrespectful calmly state: "I refuse to have this conversation with you if you can't remain respectful. When you can be respectful then we can continue this discussion." And then walk away.
Remember 180s are about stopping doing that which doesn't work, and starting to that which does.
M(53), W(54),D(19) M-23, T-25 Bomb Drop - Dec.23, 2017 Ring and Piecing since March 2018