Call the property management company in your area and ask them.They have all the data in the world for this!

Investors tend to not spend enough to acquire their first deal, not working based on numbers and calculations, injecting emotions into your marketing instead of data, quitting too early, and just not putting in the time and effort into learning paid traffic.Now I'm guessing you don't have a large budget to work with, so if your only spending $100 a month on AdWords, don't expect a deal or even a lead for a while.

I'd like to bounce some ideas with someone with experience, and would gladly share some of the data I've analyzed and collected in return for some information and guidance.

Ensure you really analyze the competition and that there is demand for 1/1 units in a rural area.

Granted our target was smaller than resi houses.. as the amount of viable timber ground was less but we were also working an area from the Oregon border to just south of Tacoma so about 100 miles by 400 miles  was our data base.. 

We have sent countless millions of offers to owners since 1999 using assessor data consolidators like RealQuest Pro (the back end of Listsource).For houses I current filter1.

Is there a site or source that compiles data on the mortgage debt that we could look and analyze.

Third-party sites play fast and loose with your data. 

What do people do to ensure the owner gets the letter and it's not thrown out by the tenant living there?

@Jon Peterson I always like to start looking at data.