Acquiring your 2nd STR is predicated on your successful acquisition and management of your first, and there are a lot of practical skills to learn on #1.  

It’s worth considering self managing as a STR for depreciation benefits if the demand is there 

I've also done some high level analysis of Nashville TN, Tampa FL, and the state of Georgia.

@Steven Wetherillwhat about property management?

To set the stage, I'm owner of a short-term rental property in the Poconos in PA and we use a property management company for bookings, maintenance/cleaning, guest management, etc.This past weekend we had a guest booking but when the guests arrived Friday evening the house had no running water, though it had been running fine earlier in the day when the Property manager (PM) was at the house to give a final check and leave the welcome packet.

Personally I consider it to be more of a entry level neighborhood for first time home buyers and a blue collar neighborhood for long term renters.

This is 100% on your desires, time, level of risk etc.

Either way, after five years, I can say I achieved a certain level of passive income—just not the kind that puts cash in my pocket. 

It isn't having paid off properties that offers security, there are still taxes, insurance, maintenance and management involved. 

Using 50% rule (expenses excluding P&i is 50% of rent) here are the numbers;1800 (rent) - $900 (expenses) - 1468 (heloc) = negative $568/monthAt your rent point with that size unit, your expenses will ve less than depicted by the 50% rule, so let’s use a likely more accurate 40%1800 - 720 (expenses) - 1468 = negative $388/monthNow let’s imagine you self manage and you time is not worth anything (I strongly recommend believing your time is worth less or worth less than a quality PM would charge) with 8% further reduction so expenses are down to 32%1800 - 576 (expenses) - 1468 = negative $244/month.