Have you investigated what types of zones, if any, specifically allow rooming houses in the market you are looking to buy in?
Many places have specific areas where a rooming house may be allowed and conversely some rules to prohibit covertly running them in areas where they are not.
For example, limiting the number of unrelated persons who can occupy a single unit. While not specifically calling out rooming houses it is a way for the municipality to enforce the ban on landlords trying to covertly run a rooming house.
@Jackie Constantine welcome to BP. Laws regarding rooming houses will be location specific. I know nothing about your area. There may be state, county or city laws that can all vary regarding doing this.
I would look for a local investors group (search Meetup or REIA) and ask people there. Also you can Google local laws and regulations.