Need advice with setting up deal with seller financing

I am representing a seller (as their agent) on a sale on a SFR in Los Angeles. The home is 80% remodeled. All systems are new and permitted with only cosmetic finishes left. The seller wants to sell next year but is open to letting it go now for a good price.

We found a buyer who offered a great price (off market). The issue is the home won't qualify for a conventional loan and they don't want to go after hard money due to the expense, and have asked about seller financing. 

I wouldn't mind this if it is rather quick, as in 3-4 months. Meaning -- Can I structure this to where the buyer gives the seller a downpayment and the seller carries the remaining note for a short time -- with monthly payments to seller -- while the buyer finishes the remodel to their cosmetic liking... after which the buyer can get a traditional loan and pay off the seller in full? 

Not sure if this makes sense -- But it sounds easy in my brain. Just unsure if the system would allow for such a deal. 

Thanks in advance!