Yes, but how can you "use" pp3 for that below plane stretch, if it is not on the same plane. PP#1 however, is on that same, below plane stretch

IMO that 'below plane' stretch, the plane of that stretch, is THE plane to be focused on, for good reason - it most approximates the plane that FORCE is traveling on during the swing, and is in effect the turned shoulder plane, or rather parallel to it.

The plane of PP#1's travel.