I don't believe the two are mutually exclusive, real estate can be both a business and an investment.

I don't want my letter to hang out with the dozen newspapers on the porch, if you get my drift.What do you guys do to find owners of homes like this?

You might check out a few advertisements for other SFHs in your area (Craigslist, Zillow, newspaper, wherever else people post rentals) and see what other landlords are doing in your area.

He almost exclusively developed from scratch and owns in SSF and San Jose, I don't think he procured much if any existing parks.  

You can get listings in the Legal News paper.

High grass, unkept bushes, news papers in driveway and lastly, mail piling up in mailbox.

I have purchased from wholesalers and I have one wholesaler that works with me almost exclusively.

As far as the funding, give NRL mortgage a call or maybe Spring Valley Bank- nrl will require 25% down for non owner occupied MFs, spring valley is a portfolio lender and may have some alternatives- they work exclusively with real estate investments.

One of his property managers has formed an arrangement with a community he manages to be the exclusive broker, and with houses wanting to sell we're at a loss of where to begin. 

@Michael Mullins We use Sammy Pruett almost exclusively in Austin.