PER-SYD-YVR-YYZ is the best I can do, I'm afraid.
At least one other guy did the whole trip with me...he was in Y, and didn't look much worse for wear than I did.
Oh wait!
I forgot I also did SYD-YVR-LHR-YYZ in one go. SYD-YVR in Y class, to boot. Upgraded to LHR, in Y coming back to YYZ.
This was the last part of my YYZ-LHR-stop-YYZ-stop-SYD-YVR-LHR-YYZ trip on a Y ticket. Used a SSWU on YYZ-SYD and the other SSWU on YVR-LHR.