There -needs- to be a way for characters to hide from OCR or it be done away with and left to players to signal the attacks, but that would ruin immersion as well.
The answer to this question is found in the formula of the Outcast Rating. Based on the race of your character, your charisma modifier, ever five levels in the influence skill rank, and what you do around NPCs, which may increase OCR, all effect your OCR.
The way to actively hide from OCR is to increase your influence rank; yes it's a mechanical approach to avoiding OCR for a largely mechanical implementation, and in my opinion a justified approach to avoiding and lowering your OCR. Influence is the combination of diplomacy(Persuade) and Bluff. If you're not skillful in either, then you're going to fail your attempts at avoiding confrontation and suspicion.
The OCR may not seem to you to facilitate Role Play, but in fact it does just that. People who were infamous in the past used to walk around freely in places where they were very infamous regardless of their attempts to hide it or not. The dms and players can not always be there to provide an Outcast with role play, but the OCR system enforces that you maintain that role play of being an outcast regardless of players and dm presence. Again, raising influence effects the OCR rating, your infamy will go down over time, and I believe if you have ranks in influence that you actually make bluff checks when you are near NPCs that would otherwise attack you on sight.
It seems to me that you're frustrated with not being able to be in the Outskirts due to OCR, however, there are locations where outcasts go. If you're character will not go to the sewers and rather die, then expect to die. It's excellent for you to Role Play a character who refuses to adapt because it can add such great dynamics to the environment, but don't expect to survive long. Don't assume that you won't discover role play outside of the Outskirts. There are plenty of people who do not return to the outskirts of Vallaki. You will find, especially if you go to the drain, that there is usually someone always there to role play with. There are ways to avoid confrontation other than a mechanical approach; just become familiar with the layout of the land and avoid the outskirts.
The only criticism I have to the OCR system is that the NPCs, like Radu, will typically outright kill you. I suggest that certain NPCs always be on subdue mode, because it does become immersion breaking when someone is suddenly killed in the middle of the outskirts for being too close to radu.