New Trailer and Off-Highway Vehicle (OHV) Report of Sale. 1. Gather required information about the seller, buyer, and trailer.You need a California Trailer Bill of Sale form to register your trailer with the DMV after purchasing it from a private party. The California bill of sale form helps individuals document data on a transaction involving the sale, trade, or gift of personal property. Edit, sign, and share bill sale trailer online. No need to install software, just go to DocHub, and sign up instantly and for free. A California motor vehicle bill of sale is part of the vehicle registration process. Use a free template to write your own bill of sale. A bill of sale is used when cars are sold in a private sale. If you're selling a recreational vehicle (RV), it's a good idea to fill out a bill of sale.