In each the one Cross-Dressing has to keep it a secret, but others find out, usually in the first couple of chapters, but keep the secret. Hana-Kimi had a nice twist in that Mizuki was unaware that Sano had discovered her secret.
What I would like is to find a series where the protagonist cross-dressing is successful at keeping the secret, either until very close to the end, or to the final chapter.
And the TV series, Sungkyunkwan Scandal, which the kind folk at B-U recommended to me, and which is SO EXCELLENT and so totally what you're looking for that you should do your best to see it. Like, ASAP.