It is one of the reasons rent by room is more difficult to manage.I have no experience with rent by room and the associated common space.  

For those who have more experience investing - what would you recommend I do here? 

Mostly people with minimal RE experience are adding a single ADU and they often make that choice based on cash flow without taking into account the negative equity position.  

I would guess that you have little or no experience running any kind of STR, and now want to get that experience on the back of someone else's investment, with little or no personal skin in the game, and that's not a good way to build an investment portfolio.

Last thing to look at (and right out of the pages of our client's own experiences) might be starting a transition of wealth in the form of using 1031 strategically to purchase property that your heirs live in until you pass and they inherit. 

The real property investment can be repositioned if it proves disappointing in its original form; it can be refinanced or recapitalized if it has too much or too e pensive debt; inflation over time bales out many bad purchases, and finally the investors knowledge, experience and abilities can be leveraged to turn around a cash flow negative property.I’ll provide an exampleThree years ago we purchased a note from a bank secured by two auto repair facilities with a large amount of excess land.  

@Kang-Li Cheng Can you expand on your experience with Doorvest?

Unfortunately, based on my experience, I'd be surprised if this is a legitimate opportunity for investment... more likely it is a means by which Eric and his team gets rid of properties they no longer want.

I've had bad experiences with US Bank and would avoid them.

In my experience, a property with multiple cottages and outbuildings can provide all kinds of creative strategies...some folks try short-term rentals or even specialized retreats if local regulations allow.