The DW has only tried backing into a site a couple of times. Hopped out of the drivers seat next to a large open backin & told her go at it. It was entertaining. The good thing is that she has an idea of what the difficulties are.
We use the radios. She talks. I do what she says. I seldom need to answer. For exact placement she stands where she wants a back corner needs to be. Gives me a 'target'.
I like to think that we are very boring to watch. There is no shouting, no standing in blind spots, no flaying of arms or jumping up & down.