My paternal grandfather was born not long after the Civil War. His first wife died in childbirth and it took him years to remarry, to my grandmother. Mourning I suppose.
From him, I know that there certainly is a way to live off the land. None of us would exist if that weren't the case. Wells were dug by hand. Cooking was done over a wood stove. You hunted, grew or foraged what you ate. You built your shelter out of materials that came from the land upon which it was built, log cabins with wood shingle roofs in the frontier east or perhaps stacked fieldstone, baked clay adobe in the west, sod shelters in the midwest, brick or quarried stone in more established settled areas. They made the brick onsite. Staples were all that were purchased and other than salt, you could get on without them. Oil for lamps, sugar, etc.
According to Diogenes Ghost the rich will survive. Us peasants are screwed. How many people can actually live in a bunker for a month much less a year. There will be so much strife in that place that they will all be basket cases after the year is up.
Indoor plumbing and running water are wonderful things, and the greatest things our civilization has given us. ;)
/johnny