This implies finding comps with ADUs that establish a value.  

However, after learning about SEC rules, it appears this may be considered a security, which would imply a lot of required compliance that I am not currently prepared to do.

This implies you are not likely to make any return from appreciation (after accounting for inflation).  

A straight up investment property implies you don’t planning on living in it, which means using an FHA loan is not an option.

Hello Gokhan,I am a contractor here in Charlotte and I do a lot of work with a company called Victory property management (changing name to MoveZen Property management) and they do an excellent job with all of us contractors and homes always seem to be in good shape, which normally implies good tenants. 

This is due to several factors such as our ability to connect with cash buyers directly and the implied scarcity of off-market properties.  

@James WiseCorrect but I was implying that you won’t need “financing” for the purchase and the rehab from an institution or hard money lender for the vacant property.

This implies you require rent above $2700 to be cash neutral.  

Your" best method doesn't imply it is a good method. 

It's akin to having a personal trainer who is 100 lbs overweight...