Of more concern would be the slim likelihood that as an Elite you would have your upgrade ex-YYZ confirmed in advance of departure. This route tends to be very difficult at times to confirm an upgrade in advance even for SEs. You ultimately may find you have wasted a SSWU for the ORD-YYZ segment and were not be able to get confirmed into J/R on the YYZ-HKG.

As for checking bags the next day at YYZ, that should not be a problem since many people who overnight between flight connections short check their bags and recheck them the next day.