When interest rates go to double digits lenders will offer a discount for paying off your 4% mortgage early.  

People think that everything double digit is risky or even smells fishy.

At the same time I am a full time Account Supervisor at a digital marketing firm who loves business/finance books over novels (recommendations please!)

Use digital marketing and direct mail for leads.  

Someone advertises how should I spend my $50K and magically three or four people have a great way to give them double digit returns.

I've been hearing on BP about new solutions for landlords receiving rent; but, I'm not sure which way to go. PayPal charges a free, as well as several others. On top of that I'm a small guy in the biz, then this just ...

Having 4-digit rents definitely comes with better tenants and less headaches.Glad you have a good team in Indy.  

But if the same real-estate principles are adopted, one could achieve close to the fabled 3-digit return?

The 4 digit house number is visible in the photo you posted.And I know the city well enough to be able to guess (based on the characteristics of the house) what area it was in.  

Here in Canada, the process is well defined and requests can be made though any police force (national - RCMP, Provincial - QPP, OPP, NF Constabulary, or local) or, in certain situations, though specificly designated agencies (those who perform digital fingerprint services, or those who can perform name-based checks)