Need advice on commercial buy with parking lot income

[Dylan Heidrich]

My wife & I am looking for a place to live in Agawam, MA. We found a commercial property (old restaurant that closed because the owner retired) thats renovated for a business but we’re thinking about adding a shower and drywall for bedrooms and living there. The owner claims to bring in $50k annually through selling parking tickets to amusement park customers. He claims he can’t show financial records because it’s all in cash and he doesn’t pay taxes. The property is only about $1k more than we’d pay for a rental so it’s not a huge risk but it would be annoying to have to move my 3 kids a 2nd time in a few months if this parking ticket business doesn’t work. 
Does anyone know of any obstacles I’ll have with this plan that I’m not considering (minus the risk of the parking business not working)?
I spoke with the guy for 30 min today and he sounds honest but it’s still a $15-$20k risk (6-12 months of rent plus cost of adding shower/bedrooms).