Being that I live and invest in Fargo, ND/Moorhead, MN, I have made it my duty to spread the importance of this distinction because I run into far too many out of state investors that associate ALL of ND and it's RE markets with the success of the Western ND oil industry.

San Diego has some very distinct neighborhood boundaries that aren't apparent if you aren't intimately familiar with the area.  

These businesses provided educational return, they got me reading books, but ultimately I failed in terms of finding personal and financial reward through them.Approximately 6 months after my realization, my wife and I were sitting in bed and I was reading the book “Rich Dad Poor Dad”.I remember distinctly, putting the book down and asking my wife “how would you feel about us selling our house and buying 2?”.

Then, factor in your knowledge of probate law and process in your state and you gave a distinct advantage of how to be helpful to the prospective admin or other PR as seller. 

You are never too old to get involved in real estate, and being young will give you a distinct advantage for the long run.If you have only read Robert Kiyosaki's initial book, I recommend you look at the rest of his books and books by other authors in the Rich Dad series of books.

Do you make a distinction between mobile and manufactured, or are they more or less governed by the same principles?

The AKC designation of the AST is what I was referring to, and the distinction between the AST and the APBT was enough for my HOA.

At the same time, I think the relative rarity of duplexes/triplexes/quads could be a competitive advantage distinct from the hundred of competing offerings in north Dallas.

Take your time and become familiar with the many distinct markets within the Cincinnati Metro area; as you may or may not know, the city has an East side and a West side that are quite distinct and then the various beltways around the city provide for other distinction.  

The eligibility matrix shows a distinction between 1, 2 and 3-4 units right?