Unfortunately, given current and foreseeable prices and interest rates, I will not be in the position to buy anything else anywhere I’d want to go. 

While the debt would whip out most of the profit for 'x' amt of time, it would seem to be logical to take on the risk at a net zero income for x amt of years if after that point, the cashflow is all positive.

People in the group are great, positive, and supporting. 

If you're starting with this model, it can be highly beneficial as it allows you to gain first-hand experience with the daily operations, actions that must be taken, requirements, market demands, and more.

Has anyone been in a similar position, or has had success offering this type of agreement to a previous owner of a property who has not yet voluntarily vacated?

We pride ourselves in keeping the forums positive, helpful, and focused on real estate (please, no politics, religion, etc.).

My advice would be to drown out the noise you hear from others with positivity and thorough due diligence.

Some lenders offer creative solutions, like a cross-collateralized loan, where they use your existing equity as security without refinancing the duplex.Another idea is partnering with private lenders or exploring a second-position mortgage, depending on your lender's terms.

If OP can lever-up while maintaining adequate reserves, he will be in better position than buying with heavy cash position.  

Those positions are hard to come by but if you can find one and get your green card, you're set!