Residential Deal might get a Appraised as Commercial

I'm currently under contract for a property (first time buyer) that has a duplex and a garage that was converted into an office space. All units are currently rented. The location is in an area that consists of commercial and single family residences. The property is currently zoned as agricultural. I am looking to purchase this as my primary residence and rent the other two units out. I have put up earnest money, completed inspections, and completed the loan documents, however there is some concern that the appraisal may come back indicating that best and highest use of the property be commercial. I am concerned that this may blow up the conventional residential loan. I don't think that I have the funds to secure a commercial loan and doubt that the property would cash flow on a 15 year term. Any advice as to ways around this? I doubt that the owner will carry financing, as he seems to be looking for cash to fund a new build. Is there any other creative financing options that would work?