Help I'm looking for any manga where the female lead LIKES to crossdress as a BOY... The o...

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Oh wait Oresama Teacher may be one. It doesn't have much of romance, though.
And Ouran Highschool Host Club.

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http://www.mangago.me/read-manga/seishun_x_kikanjuu/

http://www.mangago.me/read-manga/houou_gakuen_misoragumi/
This is the first one that came to my mind but I'm not sure if it fits what you're looking for

http://www.mangago.me/read-manga/otonari_complex/
http://www.mangago.me/read-manga/josou_kareshi_to_dansou_kanojo/
http://www.mangago.me/read-manga/gekkan_shoujo_nozaki_kun/ -> This one's pretty well-known, maybe you know it already but in case not: The one who looks like a boy and doesn't mind it at all isn't really the mc BUT she's a friend of the fmc and appears very often. Imo, the fmc and her group of friends are all mcs!
It even has an anime and ovas. Pls check them out too!
http://www.mangago.me/read-manga/9_banme_no_musashi/
http://www.mangago.me/read-manga/himitsu_no_hanazono/ -> it was never mentioned whether the mc likes to crossdress or not but I think this manga fits in your description well.
http://www.mangago.me/read-manga/koukyuu_days_shichi_kuni_monogatari/

Also this one: http://www.mangago.me/read-manga/honey_sweet_kitchen/

http://www.mangago.me/read-manga/w_juliet/

Gekkan Shoujo Nozaki-kun also has a female character who likes to wear boys clothes and has a lot of fangirls in her school.