On my last trip to the Smokies 5 years ago I hiked up to the Spence Field Shelter on the AT, there I met a couple who had about 125 miles to go to finish the entire AT trec. We talked for hours,they explained how they started overweight (themselves) with 60# packs and how they refined their gear as they hiked from Maine south. When I met them they were stickfigures, his pack weighed 23#, her's 21#, they had food, shelter, clothes, water and water purifying equipment (UV light stick). They resupplied at any small town they came near, always at a Dollar Store which they said had anything they needed.
The gal had walked most of the way with horrendous blisters on her feet, it wasn't until she found some neoprene socks that she got relief.
Perhaps if we really want to be prepared for a SHTF event we should study the experiences of modern folk who have taken on a long and arduous journey like the AT.