My goal is to start aggressively (first purchase in the next 90-180 days) growing a portfolio of cash-flowing properties to supplement my primary income and eventually become involved full time in buy and hold real estate investing.

This implies that it is difficult to include the utilities in the rent without supplementing the rent.As utilities increase, the tenants pay this increase.  

Just selling 1-2 houses per year can really supplement your primary source of income.

You're right, I need a partner to supplement where I lack. 

I offer a supplemental protection program for my clients but it doesn't cover them when the property is vacant.

It's a supplement to everything else, and a means to fund other investments (REI).Most of the information you've mentioned are what is passed through blogs, and other media that just isn't true. 

If you are looking to leave a job sooner, than make sure you supplement your rental portfolio with flips, short term rentals, or other active income.

Maybe be worth it to consider as a supplement to your real estate goals.

Their salary is supplemented in the summer by research grants.

It is not about "hiring" that makes people allergic, it is the psychology part.I KNOW you have noticed I use a LOT of psychology, to verfi data.The moment you talk about data, reasoning, psychology, people run.I believe people are lazy (sorry to be blunt), they want shortcuts, they want easy things to just work, and they don't bother figuring out why it works or why it doesn't.Keep pushing your theories forward.