OC is not addressed in WI Statutes. http://www.legis.state.wi.us/rsb/stats.html There are a thousand chapters of Statutes, each of which may have hundreds of sub-sections that may mention guns. Guns are also regulated in the Administrative Codes and Regulations by DNR, children's welfare, education - - - .
OC is not directly addressed in WI Statutes; guns are not allowed on school grounds, public property or where alcohol is consumed. Loaded and uncased guns are not allowed in cars. OC risks a charge of Disorderly Conduct.
There is a 'hassle factor', how bad it is depends on your sensitivity.