Need to have 21 Charisma and 17 Wisdom without templates.

[Eldariel]

That definitely works. Especially since most of the character's career is intended to be inside someone else's body. I can't believe I forgot about that. Perhaps because I always kinda see it as a min-maxy type of deal and write it off as not actually usable. But in this case, I'd probably use it if I can. Any other methods?

Hm, well, a Scroll of Planar Binding could get you a Succubus whose Profane Gift would enable you to push your Cha too. Or any way to access it really works. Candle of Invocation or whatever but that's bonkers. All I can think of off the top of my head; there are no stat boosting feats or classes for Cha so it comes down to point buy, racials and items, and items are mostly out of the realm of possibility due to cost outside cheesing them.