I may have come across another bit of information on Ole Johnson. I happened to notice that Isabelle Johnson had married my Samuel Hogue in Sparta, Monroe, WI. So I searched Monroe counties website and they have alot of census' online. Living with my family of Hogue's is an Ole Johnson born in Norway and is 15 years old. Could this by yours? It would explain how Isabelle and Samuel met.
Here is the link to the censushttp://www.rootsweb.com/~wimonroe/MCLHMaRR/census/1860/1860-...
Hope it helps.