Oh wow, somehow I missed this. I am pretty sure you shouldn't make a dog vomit that has eaten large chunks of anything because of the damage those chunks can do on the way back up (bruising from the force, thrust, and getting stuck crosswise in a windpipe, etc). Unfortunately, I am very experienced at making dogs vomit. It took a lot of HP to make Murphy vomit and I never followed with water. I did walk him around on lead with a big plastic garbage bag in the other hand.
My girlfriend's Doberman was vomiting liquid/water for a few days. She took him to the Vet, they x-rayed and discovered he had swallowed a golf ball. He ate ok, never vomited his food at all. I guess Turner could have chewed the corn AND swallowed chunks, too. Glad you are taking him in, it will make YOU feel better.
Big hugs to Turner!