I have a detached garage apartment that I have rented via Airbnb. 

To me it sounds like there would be many obstacles in obtaining clear title.

Location: Marin County Zip 94947Option 1: Detached any sq ft (476sq studio ft or 756sq ft are my comparisons; about $40k more for the larger one)Option 2: Garage conversion on 326sq ft (rickety garage that would probably need to be torn down and rebuilt)What is an effective methodology for comping rents when I can't directly compare to other ADU's?

The value offered is very hard to quantify and too easy to fudge.Also, in my experience, the biggest obstacles to success are rarely technical; rather, they are nearly always about your mental state, habits, and beliefs. 

Part of the obstacle is Finding an experienced Investor willing to partner up on the deal.  

What would the appropriate adjustment be when calculating the cost of your subject property when the comps have:+/- bedrooms+/- garage (detached)My market will be in the NJ area.

Purchase price: $400,000 Cash invested: $40,000 3 bed/1 bath single family home with detached 1 car garage.

@Brandon Bramley, I did house hack and also help my clients do the same.House hack is one of the best ways to get your feet wet with real estate investing. there are different forms of house hack, finish a basement, live in a detached ADU, rent by the room,....Feel free to reach out anytime.

One of the homes was a mother in law apartment built on to the back of the detached garage.

I'm very driven and determined to help people overcome obstacles they can't find a solution too, achieve success and most of all Freedom from the rat race.