I'm tall, 6'1'', MtF, and I've always had long hair, so even before I finally accepted being trans, people from behind would still think I'm a girl. I've thought about it being a problem and all, but I don't worry much over it. As long as I can pull everything else off, then I'm sure height won't be an issue. But no, I haven't been full time girl in public yet, so who knows how this will go.