How creative can you be with owner financing with out commint any mortgage fraud

[Dee Xixi]

I am in situation that i find a great deal and affraid to loose it to another investor. I only qualify for half of the asking price plus the house needs so renovation but the bank said that i can use some of qualification fund for renovation. Therefore I was planing to offer to the seller to accept my offer for the amount that i qualify for and he could put a lien on the property and I will try to refinace in 6 months.
Goes anyone have a better suggestion or can that work or is there a mortgage fraud on the process