FK – Mine is larger and does have a change of clothing because I travel hundreds of miles on my ‘commutes.’ Cotton and modern textiles will rot off or wear out after weeks or months in the outback. My goal would be not just covering ground but finding food and shelter on a regular basis because I’m not a spring chicken any more and wouldn’t expect to get home quickly unless I could ‘acquire’ a couple horses or mules.
My pack is a surplus army in multicam with a frame because I can’t afford the over-priced civy stuff and my back can’t take not having real support anymore. If things are ‘that bad’ you’d want to avoid major highways and built up areas anyway and hope you can stay hidden from over-zealous land owners. Remember, possums are your friends.
If things were ‘bad enough’ the focus might not be on ‘getting home’ so much as thinking globally and acting locally. I’ll leave the rest up to your imagination.