Probably a little late to help you now...yes, you can. Back when I was frequently working in YEG and US Airways was in Star Alliance I did it many times flying YEG-YYZ-PHL-PWM with the first leg being an Air Canada Friday night redeye that often arrived ahead of schedule. US Airways TAs were always surprised that I arrived early. I can't recall YYZ to PHL ever being full on a Saturday morning.