Personally, I kind of like the Amazons a little more remote than that with Diana being the first Amazon in millennia having contact with the outside world. It works a bit more thematically for me that way. So, essentially Diana would be the first to have contact with Queen Clea and any animosity and rivalry grows out of that situation and relationship. It helps keep Clea a Diana-centric villain, which I think is important, before becoming a Wonder family opponent. (That said, I'd love to see Donna Troy, Wonder Girl [whenever she returns], and Hippolyta to get specific villains of their own. I'm kind of sad the Myrina Black perished, because I could have seen some interesting storylines between her and Hippolyta...oh well.)
I'm not against Venturia trying to invade Themyscira after the Amazons are revealed to the world and there's a little more interaction between the Amazons and Patriarch's World. A Thunder Dome between the Queens could be quite awesome.
I guess we could have a time's past story of the Queen Clea and Queen Hippolyta meeting in antiquity before the Amazons ever went to Theymscira, but then Clea would need to be immortal. Hmmm...
This is pre-DCnU, but when Aquaman was rebooted the Atlanteans had weird thing/prophecy about blonde-haired offspring. That was part of the reason Arthur/Orin was cast out. There was an early monstrous ancestor named Kordax or something like that, towards the beginning of Atlantean history of being under the sea. I've always thought about introducing that with part of Clea's story two in parallel/juxtaposition to Aquaman and how she eventually gained power and rule despite that.
Anyway, just my personal preferences for handling Clea, AmiMizuno. Keep sharing the stories and ideas you like best! (I don't mean to shut down your ideas by sharing the things I've considered.)