This does indeed seems like a slam a what was a very productive and interesting thread , in which the OP was seeking comment, feedback, and information.

Hopelessly impractical? Well, certainly challenging, but let me cite a it of recent family history - to be precise, my wife's.

In 1918, her grandmother,living in Moscow and married to an officer in the Imperial Russian Army, was training to be a lady-in-waiting to the Czarina - not a good career move at that time.

They left in a hurry moving east through Siberia. My father-in-law was born in Ulan Bator, Mongolia, in 1920. At one point, they were saved from capture only when the dog sled carrying the family valuables overturned, distracting their pursuers. They often swapped sewing needles for provisions in poverty-stricken villages along the way.

My FIL, by way of Shanghai and Seattle, wound up at Hollywood High, where he double dated with Jean Harlow, fought in the South Pacific in WWII, and fathered and raised the most gorgeous and intelligent lady in the universe.

Those are just the highlights, and it certainly is an epic. I'll bet they would have been happy to trade it for a mere 400 mile ramble in the eastern US.

If I were to plan for the original scenario, I would adopt a hybrid strategy - let's start in the vehicle, but carry along enough that we can switch to bike or foot, or charter a helo (whatever). You never know what will come up down the way.