To follow up on your question about whether Ross might have been responsible for the design in 1915, in the July 30, 1922 S.F. Chronicle article I posted just posted in another thread, Ross talks about his experience coming to California, and he makes it sound as if his first trip to California was in 1922:
"I arrived in Los Angeles a few days ago and, of course, wanted to get a glimpse of the golfing conditions. . . I could get no information whatever as to how I must proceed if I wanted a game of golf. . . I met an old Scottish friend who showed me the courses of the Los Angeles Country Club, Wilshire, Annandale, Pasadena and the Rancho Golf Club."
So it sure sounds to me like this was his first trip to California. I guess it is possible that he or someone in his company had mailed in plans for the course at some earlier date, but it seems unlikely, doesn't it?