Tammy and Mike...
Very nice, very clear, unmistakable communication. I imagine you two will stay happily together forever!
I particularly like the "brake and stay still" method of gently reminding the spotter that all of their gesticulations are useless if they cannot be seen. Very gentle and patient method of solving that problem. I have done this myself, but I've never made a point to tell the spotter ahead of time that when I do that, it doesn't mean I'm taking a break from the toils of backing, it means I'm just waiting for the spotter to reposition themselves to find me in the mirror. I think I will formalize this technique as a communication policy ahead of time now.
I also like the hand chopping up and down to signal stay straight, instead of the waving of the arm in a "come here" or "come on back" motion, which can be misinterpreted for a directional cue, depending on the arc of the hand motion.
The karate chop massage gesture cannot be construed as a turning gesture at all. Very clever, and very distinct from a steady rotating of the hand for continuous backing.
All the other gestures I've made use of... but the above two will now be added to repertoire.