Ebooks, podcasts like @Bonnie Low suggested and start running numbers on every deal you see until you know how it all works.

To know your holes, you typically need experience.  

I am reporting every one of them now as this has gone on for years and is ridiculous that people don't know how to follow the law! 

I’m brainstorming ideas on how I can market myself to potential mentors in the STR game in order to gain experience.

I know that's vague but it's hard to be more specific on questions like this. 

The downside is that you have to share your home with a neighbor and since most of our duplexes are upper/lower configurations you will usually hear them a little - at least know when they are home.

@Mindy Jensen - Wasn't there something about how "Adding more people to title" could boost the primary residence cap gains exclusion from $500K to higher number?

Let me know if you need more ideas, I'd be happy to connect! 

Watch the house to see if they abandon it, which they probably will.Buy some books and educate yourself on how to be a better landlord.

How do I access a portion of that equity to fund the purchase of 1-2 more MFR properties in more affordable markets like OH, IN, MI, PA, TN, or AL?