We came up with hand signals for anchoring. I had hoped to find some standard set of signals but didn't find any consistency with what I found online so I came up with my own. I explained them to my wife and she then corrected them to something that made sense to her (and to her credit, were more simple. Simple is good).
She has three controls at the helm. The wheel, the throttle, and the gear shifter. We have signals which directly correlate to these controls.
To tell her direction I point to where I want her to go. As she turns the boat my arm straightens out until I'm pointing straight ahead while she centers the wheel.
For the gear selection I point up for forward, make a fist by my shoulder for neutral, put a flat hand down by my side for reverse. All gear changes have to be done at low idle so there's no reason to combine signals like hard reverse, medium forward or whatever. If she's at hard reverse and I tell her to go forward, she knows to drop the throttle, then shift, then wait for my next command.
To increase throttle I do the the whirly thing with my index finger pointed up. I do it once for 1/3 throttle, again for 2/3 throttle, and a 3rd time for balls out. To reduce throttle I do the cut the throat thing. That's a full drop to low idle.
I love doing this in front of guests when we anchor. They've remarked at how well we worked together.