What you are talking about is a tiny home which addes even more levels of difficulty in getting approved.

I have always been a generalist, master of none skilled at most. 

My property manager uses AppFolio, which is fine for transaction level detail and a few dashboards.

My debt-to-income levels, by conventional banking standards, are good but not great.

For the level of risk involved investors want 20% annual return.  

I haven’t heard the story of  the investor who rode the coat tails of a wholesaler to the same level of success but networking and building relationships with wholesalers seems to be prioritized over all others industry participants. 

I don't know your experience level but if you don't have time you could play the numbers game and carpet bomb the whole neighborhood.

This means the crime level shouldn't be high, the median income > $40K - $45K, and there should be enough homeowners in the neighborhood.What else I should care about?

That's next-level.

To be clear, I believe real estate should be owned by an entity but there are other things that are far more critical to protecting yourself personally as well as your real estate assets such as appropriate levels of insurance, well drafted vendor agreements & collecting insurance certificates coupled with understanding how to correctly operate the entity in which you form.