Good point. We sat down and came up with ours as a team and there has never
been a cross in our communications. The thumb up and down was a result of
the direction of the shift lever.

My suggestion would be to ask you wife what hand signals she wants to
use for different anchoring tasks/commands. Then YOU memorize her
signals.
The signals she comes up with, she will recognize easier because the
are more instinctive for her.
Mark E. Willliams