Probably more realistic to go to Vladivostock via the Trans-Siberian railway, then by sea to San Francisco, via Japan. This was the route by which Pince and Princess Cantacuzene sent their children to the Princess's American parents in the summer of 1917. It took a great deal of time and effort to get the necessary documentation, but the actual journey went entirely smoothly.
Of course, the young Cantacuzenes were half-American, and accompanied by their British tutor, at a time when Britain and the US were allies and Japan favourably disposed, so once they reached Vladivostock everything was easy.
Ann