It's totally all right. Anyone who says it's selfish because of promoting acceptation and blah blah is selfish because you have the right to live normally like everyone else does.
And sue the police. Only if you're a careless prostitute do they slightly (oh so very slightly) have a point. But does forgetting to lock your car make your thief less of a criminal? No. I cannot imagine a situation where rape can be blamed on the victim. At most, maybe, in some cases, there can be some attenuating factors in what the victim did. Maybe. And even if that were the case, it's certainly not the police's place to say that. Only the court can. And it'd better have some pretty good reasons for it.
Though sheesh, you really got unlucky. I've been visibly "of ambiguous gender" for maybe two years now, yet the worst I've had is a couple of comments behind my back and 3-4 people laughing/discussing discreetly. I can't imagine "hello, I'm trans" would've gotten me beaten and raped... Well, to begin with, I'm not pretty enough to excite anyone, anyway, but that's not the point.
I do think you've been really unlucky (unless you've gone and made a point of telling the most dangerous-looking people you could find), but especially with your experience, I think it's not only okay but very understandable to go stealth. To be honest, NOT to go stealth at this point sounds masochistic.
And there is no cause. Well, no cause that warrants putting yourself at risk, anyway. The only thing being betrayed here is you, by those people telling you you should once again put yourself at risk just to do "publicity" about trans people not being demons. If you want to help things, sue the police, go through a proper criminal trial, and watch as the headlines about intolerant policemen being suspended and people put in prison for raping an innocent trans person (along with the unavoidable info capsule on transsexualism that never fails to come with every article featuring anything trans) make more of a difference than a thousand more risky situations would.