The state doesn't enforce anything resembling justice for rape. Rape is rarely prosecuted and difficult to prove in a court of law.
Do you believe that the state should be trying to enforce justice for rape, or do you think it should be the responsibility of a “self-organizing” posse?
If we agree that it is the state’s responsibility, then we can talk about ways to improve it. But then, you are already not an anarchist.
The problematic parts come up with how you pay the judge (stealing from 3rd parties), jailers etc and much the other stuff the state does. It would probably be more pragmatic to basically privatize the judge/court.
So again, think of murder instead of rape. The victim isn't going to enforce a right to justice - they already failed to do so. Now what? Do you just shrug and say "you should have defended yourself better"? In that environment, can you not see how much it would absolutely suck to be a loner who is both physically and financially weak?
Worse: Can you not see that you are in fact physically, financially, and socially weak? You're going to be the prey. So think very carefully before you advocate this "utopia".
While I acknowledge the difficulties in justice with murder you're just arguing over which group of buddies is the bestest, and picking the biggest murderer of them all. Not seeing any improvement.
Now, who do you think should deal with it, your buddies or the state?