Ah-ha! I noticed that the TTB stops running at 8pm.
As I don't get in to ORD until 7pm or so, and my SAS flight to CPH is at ~10pm, I guess that sorts out my terminal-to-terminal transit choices!
I'm traveling light and have TSA-Pre; I figure on leaving the Polaris Lounge around 8:30, transfer to T5 and hang out in the SK Lounge till its time to board.