Please correct me but I am sure one or more petrol bombs might upset all your plans when dugged in.
Thousands of rounds of ammo and 10 guns does not mean that you can fight off a serious attack since you are boxed in and an average good shot never mind a sniper will get you before you have eliminated 10 attackers.
A hailstorm of bullets fired by a gang can take care of you just as fast or a bulldozer driven by a zombie.
Property will get you killed faster since it advertise your status and highly possible commodity availability.
To me survival is to dissapear off the radar screen and avoid or limit moving around unless in flight or scouting for food or water in desperation. Have reliable well prepared friends that wants to survive at your side better the odds.