It looks a bit like a stacked double wide. it is going to need some updating.

Reonomy/Costar can aggregate public data and CMBS but that is the extent. 

The cost of billboard rentals can vary widely depending on the location and the type of billboard.

I looked at a wide swath here.

Before you make your decision, check  Furnished Finder to see what the competition looks like and how many have wide open calendars to get a sense of supply & demand.

Compare the all-in $'s to putting in a 14x40 single wide, basically. 

Multifamily has a wide range of property sizes, types, class etc.

Madison was always more of a college town, so it was not impacted the same way.And MKE has a wide variety of neighborhoods with very different ptice ranges, look up Whitefish Bay or Wauwatosa, they are expensive. 

But anything you do is going to take up time, might be a lot of aggravation, and has the risk that after all the work and financial investment, might not pay off to the extent you hope for.

Warren Buffett says “wide diversification is only required when investors do not know what they are doing.”