So this is my theory, and it can def be much easier to say than do:
But I feel that it is a one thing for a person that's been labeled a boy or man to come to terms with the realization that she really is a girl, but it is a whole different and bigger thing to come to terms with the reality that she is a TS girl or woman. I feel that when people transition before they've taken that second step they can open themselves up to all kinds of problems- one of them being living with a complex about being read all the time. If somebody reads you as being a TS girl, so what? You are a TS girl! It makes you no less a girl than does an Asian girl's being Asian.
Confidence will help you pass, being a nerotic mess will not.
Another detriment to being in public before finding your peace with being trans, especially for full-timers, is this business of making up a back-story/deep stealth stuff. You've emancipated yourself from living a lie and then stepped right back into living a new one. I just don't see the benefit in that without some extenuating circumstances forcing you into it, which happens.
Don't get me wrong, I don't promote wearing your transness on your sleeve or anything, I sure as hell don't do that. Frankly, it's nobody's business and you have zero obligation to tell anybody unless you so choose, with very few exceptions. But if it comes up and you feel like you have to talk about 10 years ago (or whatever) and you'd rather not bother with avoiding the topic for w/e reason, why not be honest? Be who you are, own it, love it.
Think of it this way, if you are an awesome person and people find out/figure out you're trans, they should realize OMG, TS women can be awesome, I never knew! And you'll have done all of us some good. We all have the ability to advocate for our entire community just by living well and being rad. How easy is that?
Sure beats getting sprayed with a firehose. =P