However, our buyer's list was limited—only about 200 buyers—and after several potential buyers passed, we finally secured an offer for a $5,000 assignment fee.As we approached the closing date, our buyer began dragging out negotiations, which added to our stress.

Not sure how to approach the owner who has it listed for a great LTR rental price.

That is the most balanced and transparent approach as each party would pay directly for the support they utilize or need. 

As I approach my 20th year as a real estate broker in Texas and my 30th year as a small business owner, I've decided to think outside the box and use what I have to get what I want.  

Any advice for finding / approaching owners for off market deals? 

Here’s a structured approach to help you resolve the situation:1.

Hot water is usually separated it is just the cold water that is often not.For a very large building a flat fee is the move because the back billing and tracking of who paid for what would be hectic, but for a small MF like a duplex it is very easy.I split the bill by the fractional amount of people who live in the unit.In other words, the amount of people that live in the unit divided by the total amount of people living in the builidng.So if there are 3 people upstairs and 2 people downstairs.the upstairs pays 3/5 of the bill, and downstairs pays 2/5.No need to separate anything, you know the tenants will cover 100% of the bill and this approach is fair. 

You can use the same market approach.  6.  

This approach focuses on finding deals and connecting buyers with sellers, helping you learn the market and hone your negotiation skills.

Changes in Buyer Behavior: If buyers are directly responsible for their agent’s commission, it could alter the way they approach negotiations.