I am quite sure, that opening would be take explo ASAP and convert to Catholic ASAP . Quite possibly making yourself protectorate would be more reliable way, but Ryukyu using game of thrones mechanic... Would be something definitely unique.Its like spending cash on a girl you fancy. The bigger the target, the more they will need to be swayed into loving you.
If you consider that all my pu subjects were 2000-3000 diplo points average to integrate, you can understand why i stayed at diplo tech 6.
Anyways.. If i ever do a one tag again, its probably gonna be ryukyu.