I've come to the same conclusion. I frequently notice teenage boys with long hair that's in great condition, but they just look extra masculine from it. I know that if I let my hair spill into my face, I look like some sort of he-man (even if he-man had short blond hair.)
My best effects seem to be updos that frame the backs of my neck. My hair is severely damaged out of nowhere (plus medication shedding) and I want to cut a lot of it off to start again, but I haven't had it above my collar bone since 4th grade! And I'm deathly afraid I'll get an unflattering cut and stop passing. :/
I know a lot of FTM's do the really short hair cuts to try to be more masculine, but it usually makes them look like a lesbian.