The more time you spend talking about other options and try to build up the negatives, the less time you are spending on what you fell are the positives of your own idea.If you believe that you are onto a great idea using L2P option contracts and forming partnerships where someone else provides 100% of the money while you provide 100% of the real estate-related functions, then start it up and make it work.  

I have my personal emergency fund stored away in a HYSA, and am working to build up a15k property reserve as well, but am conflicted on where to keep that 15k. 

Do we try to just buy a modest house through foreclosure or some other screamin' deal, house hack, then build up our portfolio from there?

We are looking to do long-term rentals for a buy-and-hold strategy, starting to build up our portfolio and gain momentum. 

Purchasing subject to allows you to (1) buy a property and pay a lower rate (3-4%) that was in existence when the loan was originated, so cash flow will be better as well as equity buildup; (2) not have to qualify for the mortgage saving time, expense, and allowing property purchases in greater number than otherwise and (3) no personal liability on downside (4) no debt added to your PFS.  

While that would be nice to build up a lot of money and save, however that would just push me back even further from starting my real estate future plans, careers, family, etc.

Because I need cashflow proceeds to start being withdrawn in 2 years and not today, I'm looking for how I can build up the empire with a larger portfolio with continued investments beyond the initial $250k now.  

Are you trying to build up to some monthly cashflow # (i.e. $10k month net) or an equity # (i.e. $10 million equity), etc.

Real estate purchase using reasonable leverage, at todays interest rates, will build up equity through amortization.  

Wondering if you have advice on me just being the bank, where I purchase a house and structure a rent to own with him and have him build up a 30% cash down payment and some equity and then me sell the house to him at a locked in price.