No disagreement on the whole argument of 26" being more available in other countries/continents. I have no experience, and what Ive read confirms 26" is more available.

With that said, itd be a tough one for me to accept...I ride a 64cm frame and 26" wheels would look nuts. Appearance isnt all, yes, but man it would look wonky.
The pic below is a 62cm LHT, so 64 would be that much more circus clown goofy.




To actually discuss the issue- would bringing a 700c foldable tire and a tire boot not be enough? If a tire gets a hole in it, boot it. if the hole gets worse or its too significant to boot, use the spare. you still have a boot in case something happens to either of the new 2 current tires.
In the meantime, once you use the spare tire, then you order a new tire either by calling ahead to the closest upcoming bike shop or by ordering it online and shipping ahead somewhere. Call home and have someone send a preboxed folding tire to you if the internet would take longer or be more expensive.

This wouldnt be the most convenient to do- have to plan part of a trip around receiving a tire, but with a spare, the odds of 2 tires failing just seem low. Or carry 2 folding tires. Having a bike which fits and you love is a really important part of the overall touring equation. Also, spending anywhere from $1200 - 2200 on a new touring bike just to get 26' wheels may be out of the question for many.

Of course, all that is perception since I havent ridden much less toured in other countries.