Homemade, shop-made and travel trailers. Let's go over when to use a trailer bill of sale, what to include in the bill of sale and where to get an official template.1. Enter the date of sale at the top of the form. A New York Trailer Bill of Sale helps streamline the registration process and proves the transfer of ownership if a dispute arises. You can use the DMV Registration Guide to determine what documents you need to apply and then find office and reservation information. Use this free form for private transactions. It comes in a printable PDF format, and you can quickly fill it out using your completer.