In our24 years of experience, managing almost 100 S8 leases currently, the average S8 tenant has a FICO under 580, numerous collections from utility & cell phone companies, doesn't want to pay a security deposit, much less an application fee and claims they don't know how to fill out their S8 paperwork despite being in the program for several years - hint: they want YOU to do it for them.Most, not all, are eligible for government assistance due to a funeral-march of bad choices.REALITY: you are trust trading one set of problems for another.You can succeed with S8, but you need to understand the challenges and plan accordingly.

My understanding is the TN has some crazy rules and regulations that complicate this process.

For numerous reasons, this strategy is not anywhere near as simple as it appears, and the risk of default problems can be quite high if the seller is inexperienced or unknowledgeable.    

Two credit cards we're used and numerous memberships signed up for during that period of time.

Here are 2 articles talking about new regulations they're trying to put on STRs there, which definitely could impact your rental income, especially if you buy in an R-1 area. 

Over the past year, I've had to make frequent calls and send numerous emails—sometimes daily to MNPMC's office and the managing partner to receive timely owner disbursements.

Our goal is to start with a few small multiunit rental properties and grow from there (thanks @Brandon Turner for the numerous resources in this realm!)

Compliance issues regarding local landlord regulations not an issue in my area.

There are numerous state and federal laws related to buying and selling mortgage notes as well as originating mortgages/contract for deeds etc.You have Dodd Frank as well as numerous other consumer protection laws that you have to deal with. 

Colorado is quickly becoming on par or maybe even worse than California as far as landlord/tenant regulations.