However, insurance is limited because it only protects you from one type of liability: accidents/negligence.

@Jay Hinrichs @Steve Vaughan Looks like there's a lot of reasonable and good thinking here, but I think it's easy to oversimplify protecting yourself legally, especially if you start small and grow.

If an occupant is not following the rules but the tenant is, are their legal actions I can take to evict an occupant that isn't on the lease?

Are there any legalities, rules, or procedures for renting out unofficial units, such as an attic unit?

Is there a risk of any legal issues because of the lack of lease or lack of rental certification? 

Is it even legal to own a SFR but rent both living spaces out to different tenants as a SFR zoned property?

The one caveat about the STR market is that municipalities around the world are beginning to regulate the market so what is legal today might not be tomorrow.

Do not rely on it for legal advice.

If you want to be safe, keep anything they left for a while in case they come back for it.If all you had was verbal comment that they are leaving, you may need to go to court for possession of the unit so that you can legally throw out the items they left.

Great question - Start by understanding what lodging options are legal in River Beach.