Looking at purchasing three duplexes on one parcel, Loan ideas?

I am looking at purchasing 3 duplexes on a single parcel.  I've already tried the County Assessor and the property cannot be broken up due to setback requirements.  I don't want a Commercial loan, any ideas how to get a 20 year fixed on this type of property?  Any good resources.  Price $350,000 from the seller directly, average rent is $730, no capex required, very easy to rent, taxes should run about $8-9K/yr.  I already own to performing duplexes, one for 7 years, the other for 1-1/2.