OK, I got it. I’m not being argumentative, but let me be the devil’s advocate just for the sake of discussion.
Basically you live in a subdivision, but with some characteristics of a small town, i.e.. EMS, and some amenities, etc. regulated by a HOA. Other than retirees, I wager residents earn their living someplace else away from the development. Am I right? Three thousand homes and seven thousand residents, most depending on outside income. Should the unthinkable occur – no job/income. Those trucks bringing food and supplies likely will stop rolling, too. While odds are there are some who have spent some time preparing for at least a short-term emergency., I seriously doubt most have, and likely don’t even think about it seriously and will be nothing but dead weight. Some say we are only eight meals away from starvation. I wonder how many meals the majority of those seven thousand have in the pantry? Undoubtedly, some would pack up and leave, seeking security elsewhere. But for those remaining it would take a very strong leader, a Moses, to get everyone pulling together. It isn’t unreasonable to consider rifts to develop and people breaking off into different groups that will interfere with each other’s ability to survive and create big problems, security being one of them.
In wildlife management they refer to something called “carrying capacity”. You may be familiar with it. If not, it refers to how many species, or the number of a specific species like deer, that an area has the natural resources to support. It could also apply to your development. Does your area have the carrying capacity to support your development’s population as well as any others than might be in the general area or who simply show up? You won’t be able to isolate just your family group because those without in close proximity will want some of what you have.
Those emergency services you listed. Do those people live there. I would guess not. You won’t have those services for long.
I reiterate, not being argumentative. Just some considerations for discussion.