In AnCap, the only "social contract" like that is to not fuck with people. You can (and most would) accept a voluntary positive obligation to enter arbitration for any disputes, either by signing something like this, or by signing a contract with a defense agency that includes something like this:
And that's the difference between organized crime and AnCap: We respect another's right not to be fucked with, whereas they do not.
AnCap is GangLand. Make no mistake about it. By the way, I don't believe you have completed my first movie recommendation to you. It was Woman in the Dunes (relating, of course, to the discussion in which it was recommend). Since we're now on the subject of gangs, my next movie recommendation for you is Pale Flower.