I was always under the impression we’d go nomadic if things got bad, traveling to where it is habitatable year round and food is more available. I’m keeping myself mentally and physically healthy enough to walk long distances while not being picky about what I eat or where I sleep. I find the whole concept of hunkering down indefinitely is itself untenable.
Could you build a wood racecar like they use in the soapbox derby? I saw plans online, the kits are a couple hundred USD, but you might be able to build a cheaper one from scratch…