Calling the DNR was the way to go. I can't believe how nice they were! I called twice today, and both times a live person answered on the second ring and personally handled my call. Very refreshing.
On my first call, she assured me a 16' boat in WI has to have a title, and if the seller said it was currently registered, he in fact had a title.
If it was under 16', no title is needed, just a signed registration card and bill of sale.
I called back again after I was able to zoom in on the hull ID numbers. He was able to tell me the name of the owner, his address, when he registered it, who the previous owner was...and confirmed it is a 15' boat. No need for a title.
However, I did go look at the boat, and it is in need of a full restoration. I am interested in the motor for my daughter's boat, and might donate the remains. We will see if the seller takes my offer. Seems I am the only one to even come look at it and it's been for sale for some time. Not sure he was impressed with my offer.
Thanks for all of the help guys!