In my opinion, it's at the far end of the un-sexy-but-profitable scale.

Are there some investors who are making enough profits to participate or are these new investors? 

And my rental cash flow went from only $1500/month to 19k/month profit by taking on more loans and harvesting the equity in some of my properties including my primary.

Start small, ensure your numbers (purchase + rehab + holding + selling costs) leave room for profit, and build a reliable team (contractor, agent, lender).For financing, work with lenders who specialize in fix-and-flips. 

With your boots-on-the-ground approach, you’re in a strong position to find profitable flips.

I may have some ideas.The 100k would be their profit from the sale.

So $4,500 of additional costs to have a partnership only to avoid hypothetical risks would exceed the profits from many SFH. 

Ensuring your rental market can sustain these costs will help maintain profitability over time.The 7% DSCR loan is relatively high, and refinancing later at a lower rate could improve your long-term cash flow.

But I'm having trouble finding any properties that I could rent, BRRRR, or flip where I would even break even—let alone clear a profit or cash flow.My question is: When you hear that I'm essentially doing 100% financing, does that make it clear to anyone what strategy would be best?

While they do lose a small monthly management fee during a vacancy, they instead collect high profits from turnover charges and leasing fees for each new tenant.