What was here before?
How large is this moat that you plan to build? Is it going to be fully around your house? How do you plan to build such a moat?
I ask these questions because if you dont have a backhoe or a hyex or some earth moving piece of equipment and your planning on doing it by hand then it is going to take a long time, digging by shovel sucks balls(btdt). So not only will it take a long time, depending on how far the moat goes around the property and how deep it is, it will take time. Also with manual digging it will take energy, which means you will be needing more food and water a day then a person who is only doing say guard duty. When you do heavy labor you need your calories and water otherwise you will eventually break down, and breaking down in zombie apocalypse isnt good.
The signs you speak of putting into tall trees, what are they made of and how big are they going to be. I have been in blackhawk helicopters before and they can shoot from a distance, but not as far away as a jet, but I couldnt see far away in quality, so the signs had better be big. Maybe if houses in area are empty and roofs visible from the air then maybe paint them? Doesnt have to be a certain message, just putting something out of the ordinary on top of the houses. Maybe over several houses spell out in large letters do not bomb, remember planes/helicopters from the sky can see over a distance. I dont really know about all of this though, I dont have to worry about being bombed in my state, there would be no reason, but you live in northern virginia, and while it is isolated where you live there are large population centers within a hundred miles, washington DC is just right by northern virginia, people trying to flee then become zombies could move into the area since its not far. Also from looking at the population density map northern virignia while not as populated as most of virginia still has population, I would fear people fleeing into the area and spreading the virus more than anything. Again this paragraph is just speculation, not a area I know much about.
Trying to get onto a military base isnt a good idea in my book unless you know the people on the inside. Most likely military will deploy people there to defend it, they wont be sending everyone to the front lines to fight zombies as most people think they would. I think there would be guards, especially since you said it has a missle silo, a hanger and air strip. Also there is the possibility that military members would send their families there first, when outbreak occurs and they say the area isnt safe and they have to go off and fight, to take ID and go to such and such base for protection, take everything you possibly can and go to the base. Friends of the guards whose family members show up, and the guards themselves could be bringing along their families, and while it would be against protocol they would do it anyway, I mean soldiers have their duty but they wont let their families go just like that, they will try whatever to get them to saftey while still performing their duty.
Digging tunnels from house to house will take a lot of effort. This will lead to you needing strength and it would require you to eat more and drink more then people doing less active things. Also digging will take time and even then it would be dangerous because of caveins. I would make sure you have enough lumber to provide good enough support structures in the tunnel to make sure that they dont collapse on you. Digging a tunnel even for a quarter of a mile would take a lot of time depending on how big you want the tunnel, crawling size not as much time as a walking tunnel, but still would take time. Also what would happen if you are digging and you run into rockbed beneath the surface?
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