Seller carry back for 2nd purchase?

[Michael Healy]

So I'm in contract on a 6-unit MF and am getting a commercial loan with 25% down from a local bank. Good cash flow (10%) and fully rented in a desirable area I seem to have fallen in love with another very similar property nearby, and I'm right on the edge of being able to afford both, but it would leave me with small reserves. The bank has said I could qualify using my 401k assets, so I could swing it. But I'd rather figure out a way to buy with less down. Seller is later in life and looking to get out of land lording. Do you think I could offer seller carry back for % of property not due on sale that would roughly double what i project he's earning in monthly NOI? Would the bank go for it? I think seller could be a candidate for wanting income stream vs lump sum. He bought at market peak, though, so I think it's less about capital gains. I figure this could result in my putting down about half of what I'd expect doing 100% commercial with 25% down and would leave me with liquid reserves for both properties. Also bank currently holds mortgages on both. Any thoughts or experience welcomed.