The Trailer is to be sold free and clear of any liens, encumbrances, or mortgages. Bill of sale, invoice or other sales document – minimum requirements.An Alabama motor vehicle bill of sale outlines the terms of a vehicle sale between a buyer and seller. A New York Trailer Bill of Sale helps streamline the registration process and proves the transfer of ownership if a dispute arises. However, there will be occasion where it will not be pre-populated. Sometimes it will populate the information after a vehicle trim is selected. Filling out the Trailer Bill of Sale form involves providing accurate information about the trailer and the buyer and seller. A mobile unit is a truck, trailer or cart where food or drink is prepared, served or sold. A license must be obtained prior to operating. Buyer's Information.