My method has always been to call every listing that hit 90 days on market in areas that I want to buy.

@Treza Edwards "I am reading the Rental Property Investing book and implementing the method that focuses on cash flow and that strategy states you need to have $300 cash flow per month, per property.

Some have used this method to obtain 100% financing.

Everyone built 10 x 20'sfor some reason and they did it at the south end of town where thezoning is easiest.

You definitely want to use a thorough screening method like rentprep.com that gets their income, credit, background check, and call at least 3 references (make sure to verify them by address/job and then their name).  

What's the highest success percentage method to find a previous tenant's new address for this? 

Being a military member house hacking is the easiest way but I’m also open to learning new methods and if at all possible learning from others’ mistakes. 

If you are open to non-traditional methods of financing, you could use a debt service loan to bypass that requirement.

Not the easiest or streamlined system.

I want this to be acceptable long term if I keep this method of financing.