Currently, you can add two units to any multifamily property through the state's ADU laws (ADU = Accessory Dwelling Unit).

When you say "According to county records, our home is permitted as a five-bedroom dwelling", that sounds strange. 

This niche area does not have alot of recently sold properties and the ones that have sold are condos in high rises not single family dwellings. 

Our property was in Michigan and had sub-freezing and occasionally sub-zero temperatures, so 60 degrees is a nice spring day.FWIW, wind chill is how cold it feels to a human.  

As I need to register this business with the state and county, should I need to register LLC as "531110 - Lessors of residential buildings and dwellings" (NIACS code) or something else?

Solar is the greatest sales pitch in human history.

They add:  Creates many definitions including classes of dwellings, but specifically excludes all hotels, lodging houses, rooming houses, boarding houses, boarding schools, furnished room houses, lodgings, club houses and university and school dormitories.

Maybe see if you have a dwell in your local market?

I wouldn't be surprised except for the fact that the nice neighborhood didn't seem like the type akin to harboring dead humans... but whatever.On to my property that was under renovation and almost complete.

Your strategy of converting the garage into an additional dwelling unit (ADU) and using the property for short-term rentals (STRs) sounds like it has paid off well, especially given the unique aspects of the property and its location.Your approach to identifying a unique investment opportunity that was overlooked by others, and your patience in securing the right deal, are key takeaways for anyone looking to invest in real estate.