A number of people on this forum have spent time in places such as Central/Eastern Europe, South America and Asia. I would think hard about contacts you made. Theoretically, a few of them if they asked around locally, might find a doctor in their area who would be willing to create a vaccine passport for say $1K, which could very well be close to a month's salary for them.
I would also theoretically consider populations such as the Hasidic Jews who are strongly anti-vax and anti-mask. Yet many of them travel back and forth to Israel. So...which doctors do they use?
Which doctors do the Amish use?
What parts of many major cities at times appear to somewhat run outside American law/restrictions and are self governed? Chinatown. A place where as a kid you could go buy fireworks and knives which could not be found just a few miles away in any direction. A place where human trafficking is a massive industry. A place where things can be bought....yet a place where many will still be flying regularly back and forth to mainland China.
In my opinion the solution to this hypothetical scenario will not be found in the mainstream doctor populous unless you're extremely well connected. I would ask myself, which segments of the population run outside the mainstream liberal yuppy population, are more closed off culturally yet have a large number of people who travel regularly. I might also ask myself, while 99% of the population goes to the doctor a few miles away, which part of the population has the doctor go to them and make house visits? Celebrities. The wealthy. Also the types who probably don't vax their kids. You're never going to find Brad Pitt or Lebron James sitting in a doctor's waiting room next to you. Well, which doctors do they use. I presume in a highly theoretical scenario, a doctor would be more willing to work with inside your own home with a heavy envelope on the table rather than inside his own office. Part of liberal hypocrisy is the theoretical solution with vax's. The part of the country which vax's their children the least are the rich Hollywood celebs.
Just a few thoughts.