I would try not to tie up any of the principal in down payments.Personally, I had a family member do this same thing, but they used an investment portfolio as the collateral instead of real estate.If you play your cards right, this might be the only short-term money you ever need.Please let us know what you end up doing.

Personally if you are looking to grow in real estate going the traditional method/way of getting good properties under agreement with traditional financing will get you to where you want to go faster than trying to find all the needles in a haystack.

Really wish we would have learned how to better utilize buying real estate and finance and how life changing it can be.

South Carolina (where I live) is a great state for many things but not rental real estate.  

We're starting to see more HELOCs and 2nd mortgages on investment properties nowadays.We deal with pretty much only real estate, investors and self-employed borrowers.send me a direct message and I'll get you a little bit more information.

We were the ideal customer of a real estate investor. 

CA is hard all the way around with real estate, but if you're willing to jump through the hoops, San Diego is a good place to have a STR in a CA city.

Learning how to responsibly use debt is one of the best tools any real estate investor has at their disposal.

And if you tank you first one, there will never be a portfolio.So my recommendation is to worry less about the year one cash flow (totally overrated as a decision-making factor, yet you have to start there), instead look at it more wholeistically, opt for a less complex deal, and buy the best quality real estate you can afford. 

Hang out with others that are doing what you want to do and invest your $25-$50,000 in real estate vs education.