Fascinating, and worth meditating on! I guess you could cheat out a Mercury Venus double joy if you were to allow Caput to count as Venusian or Jovian when necessary, though this may be a dubious thing to do. Either way, still there would be no way have both Solar and Jovial joy together, as the head and neck lines of Caput are different.

Also, can I steal your letter table at some point? It shows very clearly something that I have wanted to be able to explain concisely but always needed a lot of words to describe.