None of the homes were bought with the intention to rent them out, so the sale price and mortgages weren't optimized to be rentals.

Even reading through your scenario I felt a bit of overwhelm, and that is what I want to draw from in my advice:I’d recommend limiting what you are looking at right now and seeking to optimize one thing at a time.  

Now you can educate more / optimize. 

Apply this concept to many areas of your rental areas/homes.Good Luck and keep that momentum and optimism going!

Some methods (amongst many)Well functioning websites with SEO optimization, TV ads, mailers (yellow letters, bandit signs, bird dogs, driving for dollars, networking, foreclosures, estate & divorce attorneys.

Only a small amount of investors are optimal for residential land lording.

You wont knock it out of the park, but a solid earnings stream might be had.The other side of the coin is a poor TK provider might sell you a property that has hidden issues and a poor tenant in a sub optimal neighborhood.I don't think its one or the other, I think the vast majority comes down to  the integrity and market conditions at the time you buy.

People are either not accounting for ALL operating expenses and will take a cash flow haircut due to ignorance or unrealistic optimism or just want to slumlord it, are banking on appreciation, or are buying as a house hack but again are not thinking about the property cash flow on its own down the road when they move out.

A lot of investors who are not able to qualify for a traditional loan on purchase go that route: no W2 income, well optimized tax returns showing no income, ect. 

Second, you are currently busy so you may not be in the best situation to learn how to optimize your investment to get the best return you can.