PRO: these are short term loans (usually repayment should take less than 1 year MAX).

This could be potential for short sale, though.

We can use end buyers funds to fund the transaction, as long as it's not a short sale and the end buyer is using cash or hard money.

And that banks have a seasoning period? 

Some will lend on that after a short seasoning period, say rehab the property and get a tenant in it.

With 5 mortgage payments, PLUS rental, we would be able to achieve full ownership of the property in a (relatively) short time span.

A short cut of sorts, that EVERYONE can take advantage of.

Short of "foot knocking" and "driving for dollars" I cannot think about manny other ways to find what you are looking for.

How does using ONLY operating expenses for one year period determine a return on your investment? 

If they commit to signing the Lease Agreement within a specified period (usually 30 days max), I convert this "Holding Deposit" to the Security Deposit (fully refundable, minus items above normal wear/tear).