I completely agree with Keygrip's comments. If one is flying and the other doing R/T then that isn't really CRM as there is no specific flight oriented goal ascribed to those divisions of tasks and activities.
I totally agree with this comment and that begs the question should there be a custom CRM designed specifically for two pilots sharing a private light GA flight?
One should be that in light GA only the handling pilot should touch the controls or engine management, flaps, gear etc.
Pace