If you want to defend your home there are many easy ways to do it without digging trenches. Common plastic trash cans filled with sand will stop almost any bullet. Stack these in front of firing positions in your home and in the second story and you now hold the high ground. They cannot see you and you hold a great defensive position. It doesn't take very many trash cans filled with sand to turn you home into a fortified position. Remember when the shooting starts the neighbors are coming to help because they know they are next. Look up flanking in your acme survival book.
My home, surrounded by vineyards and a 9 foot deer fence all the way around will make it slow going and deadly for anyone to get close to the house. You are not going to get inside the fence without the dogs alerting us.
Water and food in not a issue, just the people who are trying to take it from us.
The very thought of well armed bands of mobile thugs is pretty ludicrous. Driving around up here like that will get you killed in short order. Gee look honey there goes 8 trucks of armed men, I wonder where they are going. Plain and simple they are going to get attacked and killed. Remember in rural settings they will have to bring everything with them. They lose a truck and they lose those men and all those supplies. Think of the road to Bagdad and the gantlet the Marines had to face. Now try that without air cover and M1 tanks and Bradley's. Try it in a Toyota pickup. I wonder how a mini van full of bad guys holds up to a IED. I wonder how a bunch of rednecks hiding in the rocks and behind trees would fare against a bunch of thugs in trucks, its called a slaughter hole.
Get to know your neighbors, there is strength in numbers. I go to church with mine.