So I'm wondering if anyone here has any advise or guidance on structuring a Subject-To and Seller Financing Hybrid Deal? I have a Seller who's open to getting creative with the sale. The basic structure I have is as follows

Duplex Renting at $550 bottom (700-750 Avg) Top Unit Vacant - Est of about 10k to make it rent ready for both units. ARV $110k

Asking Price $85,000 - Mortgage Balance of $72,000 = $13,000 to walk away with. The PITI Monthly Mortgage is $370. (sub2 part)

Seller Financing Part - $13,000 with 7yr Balloon amortized on 30yrs with 2% interest and $4,000 Down Payment. $9,000 Financed @2%.

My monthly payment based on a balloon mortgage calculator would be $25 (Seller thinks that's a joke) and wants at least $100/Month

How can I structure this where I can meet his $100/mth + $370 mrtg + expenses like maintenance and management and my Wholesale Fee of course! 

This is located in Toledo OH if that makes a difference. THANKS IN ADVANCE!!