MultiFam Current Owner Wants to rent

Okay, here is the deal

Duplex 2bed/1ba per side, separate private yards
Seller wants to rent one unit after close until his new construction is done.
I want to live in the other unit.

Now what i would like to know is how can I structure the financing on this so, that I do not come out of pocket with anything.

I was thinking have the seller deed it to me, and I could take it sub to, and just have the seller pay whatever the current note it. Then I would do a refi is like 6mo to a year cash out and pay the seller, whatever we agree to. I would like some cash flow, but since seller will be living there he may feel a bit stiffed pay more rent than his current note, so I can let that go. But I will say that the seler said that the units rent for 1k, so I would assume that he is expecting to pay as much. Also I don’t know what his current note is. And the problem with the refi is, at the moment my credit is poor. I am having a few things removed but truth be told I want to refi and cash out ASAP.

SO any advice, and any tips on the deal structure?