Financing options for a 4 unit building?

[James Bartlett]

Context: I currently manage 10 units. Out of those 10 I own one, a single family home. I just purchased this house this July which drained most of my savings as we did a conventional 25% down. The other 9 units I sublet on varies platforms like Airbnb, Vrbo, etc. I’ve had over 600 tenants in the past 3 years so pretty good grasp on managing tenants. This is what I do full time, and is my main source of income. 

Situation: I want to purchase a 4 unit a building I already manage and the owner is on board with doing a seller financing option. 3-5 year balloon. Not sure yet on a down payment amount. It may be 30k to 100k. Which I know, is a big difference. 

Problem: I'm out of cash. I just spent everything on this new home. Additionally, I may not qualify for a HELOC on my personal home. After calling the bank, my net income isn't high enough. Obviously, when you write off literally everything you can your net income goes down.

I pay 3450.00 a month for the 4 unit. I could afford to give an additional 1000/month if the owner would accept no down payment. But in his words, "I’m gonna be dead soon, I’m 75 and would like down payment money to go do something with my life. While I still have life to live."

I’m currently in the Army reserve, if that matters, maybe someone knows military friendly lenders more than I do?

Thanks for taking the time to read.