I suppose there is another problem as I’ve given it further thought. You don’t want the audience to be mad at Rey for not taking up Kylo’s offer, which is why making his offer too tempting compared to the alternative is risky. In this case, it would either be running away with him, or going to Exegol and almost assuredly becoming Empress. Especially since Kylo is seemingly okay with forgoing power over the First Order, I see absolutely no reason why Rey wouldn’t accept his offer. And since she has to decline, I think most people would think she’s being idiotic. Remember, the only reason she declined Kylo in TLJ was precisely because of his urge for power. And on that note, after she heals him, I see absolutely no reason in this new chain of events why she wouldn’t tell Ben to come with her to Ahch-To, as she’s finally come to terms with the idea that he was right all along. The reason why she doesn’t do this in the original TROS is because she is still under the impression that he wants power, and leaves before she realizes that he’s changed.

I’m not commenting these things to bash the idea, I just want to clarify any possible problems with it so that fixes for these plot holes can be thought of before any real work begins. Or perhaps so an entirely different idea can be thought of if this one has too many holes.