Well thanks all for your advice and suggestions! I am HAPPY to say we called the Battle Creek Amtrak station directly this morning and the phone was answered almost immediately. The agent asked for our reservation number (it was already paid for), looked it up and immediately said YES, come to our station and I can print this ticket for you. He had the voice of an experienced ticket agent.
So we drove to Battle Creek--a pleasant and scenic route through several interesting towns. We arrived at the station and saw a large dedicated and windowed staffed office area. We told the agent we were here to pick up the open sleeper ticket. He said this is such a rare transaction I still remember your reservation number. He typed it in and we had the ticket in our hands in less than one minute. He was clearly knew what he was doing. He said again how rare this kind of ticket is and he knew almost all agents were unfamiliar with it.
And the ticket is exactly what I hoped for! All identifying details are present for the conductor to view when we board.
I am very glad we went to Battle Creek. Yes, it would have been easy print it in Chicago (baring any unforseen circumstances) but it was totally worth it for us. It was a pleasant drive and we even stopped for lunch.
Thanks again! Looking forward to our train trip. All's well that ends well!