Mr. Rawles,
I think that some attention should be paid to implementing psychological deterrents as a measure of improving retreat security after The Crunch. As food and water sources are depleted in the cities and the surviving population begins to mobilize you will more than likely see refugees passing through your retreat locale. These people may be armed and will be tough as they have survived to this point, but
mentally they will be tired. When they approach your compound they will view fences, antipersonnel barriers and armed conflict as obstacles that can be defeated. The point is to try and keep them from getting to this point. If you can create an obstacle that is impossible to beat they won’t even consider it.
What I am suggesting is [simulated] NBC (Nuclear, Biological, and Chemical) threat through the use of markers. Almost every adult is familiar with these symbols and their related colors and will probably do whatever they can to stay away from them if they know that there is a threat. So I would suggest that in areas where you feel that people may be traveling and wander into your territory that you use one of the placebo markers. You could even fashion some fake graves near the area or spread animal bones. [Most] people will not know the difference. Upon seeing these people may immediately rethink their route and destination and avoid your retreat.
To add to this, if the scenario is bad enough such that there is military conflict you could even use fake anti-vehicle/personnel mine markers. You could even combine the two–such as placing a burned vehicle with a scorched area around it to mimic an attack with depleted uranium, and then place nuclear hazard signs around it. I know that it is may seem cruel to play with people’s minds, but if they were to accidentally wander onto your retreat and pose a threat then their lives would be at stake. Regards, – Echofourcharlie