Abstract: An extendable boat trailer is comprised of a first length of square tubing secured to a trailer support frame. The first length of square tubing has two apertures therethrough inwardly of an open end portion. A brake light receptacle is secured to an upper portion of the first length of square tubing. The brake light receptacle has a length of wire coupling with a tow vehicle and a trailer's brake lights. A second length of square tubing has three apertures formed therethrough. The second length has a butt plate secured thereto. The second length is adapted to be received within the open end portion of the first length of square tubing with the two apertures thereof selectively aligning with the three apertures of the third length for securement therewith by a fastening device. A trailer hitch is secured to the second length of square tubing. The trailer hitch is adapted for securement to the tow vehicle.