We will be converting the garage into an Accessory Dwelling Unit (property is in Los Angeles). 

It was a 3/2 and 1/1 with a separate garage (I planned to turn into an accessory dwelling unit - did not matter if permitted or not at that time).I chose to live in the larger unit and rented the 1/1 which covered 40% of the mortgage...if I did it the other way the 3/2 rent would've covered 75%.

For example, we wanted to build a two stall garage with an accessory building on a property close to a lake that my in laws could stay in when visiting separate from house as well as an office area away from our loud kids. 

Aside from this, I’d look at a house with a legal permitted accessory apartment and either rent the apartment or live in it and rent the main portion.

it seems permitted in your countyhttps://planning.saccounty.net/Pages/Accessory-Dwelling-Units.aspx

Long post here, but I am considering putting an offer on a property in Montgomery County, Maryland and converting the basement into an accessory dwelling unit. 

(Its craft show season and I dye, spin yarn, and knit apparel and accessories.  

The area is zoned for mixed commercial and residential use with the allowance of accessory dwellings.

However, if they're not technically separated, then I think you could live in one and the other would be considered an accessory unit, which IS allowed under the Aurora Airbnb law.

In case you haven't already done so, make sure you ask the zoning officer 1) if this 3rd rental unit is allowed in your zone (not as an "accessory apartment" but as a full-blown rental unit based on the zone the property is located in, and 2) if you'll be able to sell it as a condo down the road.