The form consists of the significant vehicle, buyer, seller, and sale data, along with affirming signatures from both parties. County of Harris. §.Used trailer less than or equal to 4,000 lbs. Names of both the seller and the buyer; Detailed information on the trailer; Date of sale; Price of transaction. Edit, sign, and share TRAILER BILL OF SALE online. No need to install software, just go to DocHub, and sign up instantly and for free. All trailers except farm trailers must be titled and registered in Texas. When transferring ownership, use a Texas Trailer Bill of Sale. A Texas Trailer Bill of Sale is a legal document used when transferring ownership of a trailer. The Texas bill of sale form verifies the elemental facts of the sale of personal property in exchange for a predetermined compensatory amount.