Seemingly you have read everything on the forums so I don't know if this is new to you or you may see it in a different light. This is Coach Stuart giving advice to Joel.
When I start sucking water, I tend to go back to what Stuart says here about breathing with your spearing arm and it's momentum. So as the left arm spears with momentum turn your head away from it towards to breathe. Couple this with a popeye/fish hook mouth and you will be in air every time.
I usually breathe to my left for a length and then to my right for the next length. This means that I only need popeye to one side at a time. Due to co-ordination issues, I have been known to make the mouth shape the wrong way when swimming bilaterally. Which brings me neatly on to..........
......there was a video, (I can't track it down at the moment) of Terry lowering himself into the pool with his mouth open, until the water level was above his chin and the bottom of his mouth had water in it. He then practiced breathing normally through his mouth over the water in his mouth. This I think helps with "water touching mouth" shock.
On days when it's not clicking for me, I can end up swimming many lengths with water in my mouth.
I hope this helps. It's all I can do as my wife won't let me hug you.