An RV Bill of Sale is a legal document that serves as proof of the sale and transfer of ownership of a recreational vehicle (RV) from a seller to a buyer. The proof of sale for a vehicle from a dealer is the Retail Certificate of Sale (MV-50) ("Dealer's Bill of Sale").A Recreational Vehicle (RV) Bill of Sale is required anytime an RV is sold or transferred between a seller and a buyer. How do I fill this out? This is typically one of the first items you'll put on the bill of sale. The seller must complete all applicable information and sign this form. The Bill of Sale or Even-Trade Bill of Sale must be notarized.