Interesting observations Jim.
Not being a qualified naval architect, (but I know who is) I’m not sure I can comment.
From my dinghy sailing days, I recall that the main object was to always keep the boat upright so as to maximise drive from the (upright) sails. Maybe an old wive’s tale, but it seemed to work.
The other drag is the rudder; there are those who advocate a tad of weather helm. I would have thought that neutral helm (ie with the rudder right onthe centere line) would be best so as to eliminate drag.
Then the really keen racing Atalanta skippers would advocate lifting one or other of the keels. My advanced years precludes this option.
To answer your question though, there must be someone who can interpret the underwater shape of the 10 to 15 degree heeled hull, displacement, sail plan etc and reach a definitive answer.
Mike