Don't overthink it, people that got fined or even deported for working on their property were asholes looking for trouble with their neighbors (and therefore got reported) or lived in touristy areas where labor dept rules are strictly applied(let's say you renovate a townhouse in central Chiang Mai and people see you hanging outside painting it, that would be high risk). I looked up Chiang Khan, you are in the middle of nowhere... no one will ever bother you.