I've tried.
But Yamato's case just seems like a coping mechanism and childish fantasy she uses to deal with the trauma she had to endure.
Kiku's case doesn't feel, at all, similar to Yamato's.
The things she idolizes about Oden have nothing to do with the fact oden had a dick or a vagina. He was free, adventuring type, "badass", etc.
She doesn't need a cock or "be a man" to achieve any of that.
Maybe Oda's intent really is portraying Yamato as a trans man. But man, he does an amazing job at overcomplicating it then.