Yes, I did read your first sentence, and I responded to it.

I said, "a lot of little towns have sporting goods shops and/or hardware shops where you might be able to cobble together a temporary solution". They might not have exactly what you want, but a relatively handy cycletourist could figure out a solution with what's available, at least temporarily.

Before I started cycling long distances, I took a maintenance class that specialised on how to make repairs when you're out in the middle of nowhere. It was a good class and I highly recommend that if a person figures they're going to be some distance away from a bike shop, they take such a class.

And regarding tubes of the right size, if there's a service station, chances are you'll be able to find patch kits. Just the other weekend we stopped by a service station in a little dot-on-map town in northern Tasmania and picked up a pair of patch kits.