Then you can usually eke out a small profit on the rental income if you self manage and pull your money back out so you can scale with that. 

I'm wondering if there something like them but on a bigger scale.

I also don't know how day-to-day you are involved with your deals, but it sounds like what you are running into is a scaling problem (private lenders aside) - you can't do more deals because you don't have the bandwidth to do more. 

I'm currently working on scaling up quickly through purchasing large SFR portfolios and/or apartments, and I'm in preliminary talks with a few sellers willing to carry back a seller 2nd note of 20-30% (i.e. the down payment).I'm looking for a lender that will move forward in financing the initial 70-80%, in 1st position, alongside a seller 2nd of the remaining 20-30%, totaling 100% CLTV.

Both private money loans and hard money loans are popular alternative financing options, but they’re different in key ways.Private money loans are like borrowing from friends or family, but on a bigger scale.

I've scaled through turnkey, BRRRRs and everything in between. 

And even if you are slab on grade, a poorly waterproofed shower/pan would likely let water into walls then the slab.  

What types of funding structures have you found most effective for scaling your real estate portfolio? 

Networking with others who share your goals will be crucial, but having that firsthand experience will make scaling much easier.

Personal assets (home, car) and W2 income. 4 Single Family rentals, and looking to scale up