You can check bags for next days flights in T5, I've done that to ORD a few times. Make sure you checkin online and complete all the APIS, then you can even do it at the kiosk and just hand the bag drop your luggage.

The only place that doesn't accept evening luggage check in ARN is the domestic terminal, they don't have storage in the luggage center. Thru check from international arriving at T5 for next days SK domestic is OK, they just store it overnight in T5 and lug it over in the morning.