Thank you for adding more to my post.

Which is perfectly legal in OBR, provided said foot is still in the box.

I make this call once or twice per year. This year I've called it only once--in a summer collegiate league game down here in the Lone Star State. Batter bunted, but before he did, he positioned himself for the bunt by taking his left foot (a left-handed batter) and placing it directly behind the point of the plate, well away from the box. It was obvious and blatant. These are the only times I ever really make this call. (Similarly, when a batter makes a "running bunt" and is halfway to the frickin' pitcher's mound when he makes contact.)

I had a Legion coach on my case about a batter hitting the ball while out of the box, the problem was the lines of the box were completely gone. I asked him how he proposed I call it and his answer was, "well you know where the box is supposed to be". I told him , that unless we want to stop the game and redraw the boxes, which I will not do, he needed to zip it and be quiet.

I have called out of box at contact a few times, not many. Never with foot behind plate, always with foot entirely on the plate, or entirely in front of the plate, or entirely out and in front of the box. It's not always a bunt, but usually. It's not too hard to call ball/strike and see a foot on the plate at same time. Probably not more than a half dozen calls in 25 years.