I found Jan Visser in the civil registry, after I found his earlier trip to the United States (mentioned on his record for his second trip), which gave his father's first name, Ruurd -- the second trip, with my great uncle, only gave the first initial. I think I've also found Jan later on in California (actually, I've definitely found him later on in California, applying to naturalize in Inglewood, but I think I also have him in SF in a city directory). He married a woman who was born in Mount Vernon, which comports well with what I know of Hein's travels (and which is more or less where my grandfather settled). I'm still waiting for Skagit's marriage records to show up in Washington State's digital archives, however, so I won't be able to track down much about her until they come online.
This entry should be considered more in the spirit of a note to myself for later.