For instance, if he has $19k equity in a car, you could give him a reasonable interest rate with the car as collateral.

Difficult to obtain because they want collateral, which puts me personally at risk. 

You should then receive a physical collateral file if not already an electronic one - Collateral file is a a file which contains all of the previous mortgage paper work including things like alonges, deeds, borrower personal information such as bank accounts and credit scores at the time of the sale, pretty much all the paperwork submitted, required at the time of the sale. 

Promissory notes are basically loans that also have certain time frames and are often secured by collateral.

Does that mean that lenders of a traditional loan on investment property in a Non Recourse state can not go after personal assets except for the collateral property in case of default? 

The bank is saying they can't release it from the loan because the total value of the other 2 buildings isn't enough collateral if they release that duplex.

I owned a property outright, used it as collateral to purchase another property and cash out equity in the first.

The owner keeps the property as collateral. 

Or if you have some collateral that you could use as leverage that might help as well.

They could sign the land over and then maybe you could get a construction loan and use the land as collateral for the loan.