I was able to reach Sprockets Bike Shop in Santa Cruz, who had built my rear wheel. Kathy found a suitable replacement rim, and will ship it overnight to the motel. So I should be able to get it rebuilt on Wednesday, and hit the road then or on Thursday.
I visited a sports/orthopedic doctor in the afternoon. I ended up paying $170 for a knee brace, a prescription for anti-inflammatory drugs, and an opinion that having my knee problems is not good if you want to live on a bicycle tour. And he thought that I could move my seat back a bit. This, of course, is opposite to the suggestion from my doctor in Santa Cruz, but I'll try it. It will require having another hole drilled in the seat support, as I'm all the way back on the seat adjustment, but I should be able to do this with a hand drill and tap.
Having finished my paperback book, I headed to the only bookstore in Turlock, which sells only used books. I am amazed that there isn't a full-service bookstore in town; everybody seems to go to the Barnes and Noble over in Modesto (about 12 miles away). Contrast this to Santa Cruz, a town of the same size, which has at least four bookstores, with two of them within a few blocks of each other!