+1 on what Wiley Coyote about small towns. FYI, a town of 500 might have a mechanic but a town of about 2,000 will have a doctor and grocery store. 2,000 seems to be the critical mass to support both a doctor and a grocery store which are vital (even though the grocery store may go under it could always serve as a logical location for a market). Once you get over 5,000 people in one town you start seeing a lot of deadbeats. Beyond that, you've got the county level which hopefully will have less than 20,000 but ideally be closer to 15,000 or less in population.

A small town is the best setup because it works in good times and bad. Communes and ad hoc retreat communities struggle in good times (why are we doing all this?) and they struggle in bad times (Why am I doing all the work compared to others?) and there is always a power struggle over money and resources. It's not impossible but it's difficult. At least in a small town, everyone has separate lives and separate property rights until they decide to come together to defend the town.

Blood ties are the strongest there are. Our culture has burned into us respect for our elders and trust among immediate family. Now if you're in a dysfunctional family now, then all bets off, but if you family has a firm footing in the 10 commandments then that's the group you want to start with.

Kurt Saxon wrote quite a bit about this topic if you're looking for further reading.

So to get back to the original question - my answer is that your group should be your immediate family quickly followed by 2,000 folks... a small rural town.