I think it's necessary to devise a number of sub-locations for the initial "triage", and then key spots for the next stage of transitting to the final destination.
#2- you really have to get personal with the people you're going to meet up with. I mean, you have to know who and what they really are, and decide if you can tolerate the differences enough to keep those same differences from becoming problems, because eventually you'll be sharing resources/caches, etc. and you want to know you can trust these people to the utmost.
#3- people have to get real. Some have training, and some have none, and some think they know what they really don't know.
It takes dedication and effort and most of us really aren't interested in spending the time and energy to KNOW what will be required of us.
I know there are a few in GA that practice. One place to get in touch with these people is on the survival board on Arfcom. There are ocassional meets in state for camp outs and such.
To explain a bit of what I mean in #2- let's take a basic example. Let's say there is a violent proactive , aggressive enemy that will seek out those hiding/ providing for themselves as the enemy recognizes it as a threat.
say there are three familys that have teamed up. Couple #1 are in their 20's, healthy, capable, but not experienced in outdoors life. They have no children. #2 is in their late 40's or early 50's. Kids are gone. They are prepared for the life away from normality, but health is less than ideal (maybe necessary medical issues (diabetes). #3 have a child of 4- and an infant under 12 months, the couple is in their 30's, and share similar capabilities of the others.
When things get hot- a few periods of close calls or contact with the enemy, and it's a bit too close for comfort- what happens when couple 3's baby starts crying, risking exposing all to the enemy? What happens when they can't move as fast because of the baby, or the other kid gets sick? Or #2 has health problems that's slowing everyone down? Or they want to try to contact their kids?
These are the things that I think need to be thought out before inviting a group of people to be close.
Desperate situations will test the bond formed, so choosing wisely will resolve a lot of issues before they expose themselves.