Last I read, WN does not have interlining with anyone.

You can still get your WN boarding pass before your CX flight if you have access to a computer within 24 hours of your WN flight. You can also do CX pre-checkin from a computer (CX called it "online checkin", but you do not actually get a boarding pass; it does let you speed things up by pre-entering your passport information, and it lets you change your seat assignment with a seat map view).

I made it out of a CX flight through US immigration and customs at SFO in 40 minutes, but that was a flight arriving at about 14:00, and I had no checked baggage. An 11:35 arrival will arrive simultaneously with several other large planes coming from Asia, so the line at US immigration and customs will likely be longer.

Schedule your return with a generous layover between your flight to SFO and your CX flight leaving SFO (regardless of which airline you fly to SFO). Flights into SFO are frequently delayed due to weather, though this is more likely to occur with short domestic flights than overseas international flights.