So, if a “typical” transaction would require 20% down payment to go along with an 80% institutional loan, then if I brought in a couple of investors who funded 10% each and I as “sponsor” received a 33% ownership interest as “promote”, I would have used OPM for that 20% down payment. 

Have you tried reaching out to your states office of financial institutions.

Amongst the common misconceptions I see by posters on BP are that hard money loans are junior mortgages to fill the gap between institutional financing and down payment; that it is in lieu of down payment so the borrower can acquire a property with “no money down”, and that it is money borrowed to use for an earnest money deposit.

It may change state to state.I recommend joining your local ULI group (Urban Land Institute).

If the seller subordinates his seller financing and mortgage to the institutional lender you won't have a problem.

You need a pre-approval letter from your lending institution. 

It will be hard to get a loan from and financial institution if you’ve got the IRS breathing down your neck!

We focus in 12 markets in Florida, including SW FLWe are a long time property provider for some of the bigger podcasters: Real Estate Guys Radio, Marco Santorelli (Norada), Kathy Fetke (RWN) Jason Hartman ( Empowerd Investor) GRE (Keith Weinhold), Whitecoat Investor Group, Jake & Gino and more We have built over 9,000 properties and work with over 1,000 investors We also work with American Homes for Rent, Invitation Homes, Crescent, Haven Realty (JP Morgan) to name a few on the institutional buying side.

This is exactly who most syndicators target.Then you get into family offices and institutional money, who can write $5mm+ checks.  

Too big for mom and pop investors and too small for institutional investors.