Living “off the grid” to most people sounds like something only someone with a secret to hide might do — but the truth is, when it comes to the end of the world, it’s going to be the safest place. Not only are you likely already well out of any nuclear and zombie-attack range brought about by big cities, but if you’ve been doing it for a few years and are settled into a regular day-by-day operation, you’re going to survive a lot longer than anyone in the city who thinks it’ll be easy. Maybe they know about water filtration and...