Motor Vehicle, Mobile Home, Off- Highway or Vessel Description. Year. 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.A Recreational Vehicle (RV) Bill of Sale is required anytime an RV is sold or transferred between a seller and a buyer. The form also documents the sale and is the legal receipt. This document serves as proof of ownership and allows the seller to report the sale to the DMV. The form includes the details of the vehicle.