What was the reason behind the poor credit history? 

@Avtandil G.Yes per @Russell Brazil- all you may need is the three years of rental-income verification - if possible, otherwise justcurrent tenant rental history, lease details etc.

However, being that you just starting out and plan on using leverage (aka mortgage loan), I can more than likely suspect you do not have a credit history.

Springfield is in a rural area of the state near the eastern panhandle.

Banks usually want to see a history of rental income which I believe is a year plus.

Look into naca.com they lend based on payment history, 2 years of on time payments, and not credit score.

The mastif is 8 yrs old, already gray in the face and basically just lays around all day.Overall otherwise great candidates with income (3x rent), credit scores (over 600) and past rental history (8 years at last place). 3 questions:1) would you rent to them and allow the dog?

@Pat JacksonWhat others have said in regards to interest rate on the note, value of home, payment history (highly recommend using a servicer and not servicing yourself), LTV at time of sale to note investor, records of payment history, market conditions and a number of other factors are all great points.I would say that most performing Note investors are looking to achieve a 12-15% yield. 

All have good credit except the number three pair where hubby has no credit history because they work for cash 

It had everything I was looking for, could be zoned as a hotel, qualifies for Historic Tax Credits, has lots of history, and room for 14 airbnb units!