Clarification on contract for deed

[James Bartlett]

Context: there’s a 4 unit building I want to buy. I’ve been managing it for about 3 years. In a nutshell I sublet properties for other landlords for a living. I own property too but this style of management is how I pay bills. I’ve paid over 100k in rent on the building over the 3 years. I mentioned that only to highlight a reliable track record of payment toward the building.

Problem: I'm trying to avoid another 25% down. I just spent most of my money on a traditional sfr purchase. I own my personal home so not sure how a house hack could even be possible. If a bank wanted 25% down it would be about 125K. I can afford to give the owner about 50K. I have talked to a couple lenders about a HELOC but because I'm self-employed my income looks low because of all the deductions at the end of the year. Because of this, I can't get approved for much.

Question: If the owner agrees to carry the loan for a couple years then I go to a bank to refinance, will they require another down payment on the building?