Not much to report, except that I spent most of the day worried about the problem with visas. Indeed, the problems associated with getting a Chinese visa appear insurmountable. Reportedly the Chinese want you to get your visa in the country of your residence, no more than a month before the start of travel, and the backlog is such that it takes up to 30 days to get the visa. Sounds like a catch 22 to me, so with tears in my eyes I am beginning to think about alternatives. One possibility is to do the trip crossing only Russia, from St. Petersburg to Vladivostok (and from there to Los Angeles and Mexico), as I had originally intended. The Russian visa is still a challenge, but at least it is only one visa problem to deal with. Another possibility is to fly to Thailand, and from there jump to Indonesia or Philippines and from there fly to the US (via Hawaii) and from there to Mexico.
Arghh, visas are a medieval annoyance to the modern traveler. I like the way the Malagache do it, where you get your visa at the port of entry. In that way the country collects a fee for receiving visitors, but one major barrier to tourism is minimized. Of course, there is always not having any visa requirements for short-term tourists, like in the countries of the European Union, which is absolutely civilized in the 21st century.