This is so simple I almost did not metion it. But it saves the hassle of fumbling with wood scraps to protect the transom when attaching a motor. Plus, the weight of the motor is on the back of the seat (red arrow), which in turn rest on the stern lock, thus distributing the weight to the entire stern rather than just the transom.

Two pieces of scrap wood are cut to 10 to 12" long. One is placed on the seat and marked at the top of the transom.  Trim both pieces to that width.

The piece above was sanded and finished. A strip of double sided carpet tape was stuck to the rear at the top edge, and a scrap of PVC cloth attached. Most any durable scrap would work, even clear vinyl.

Lay the hinge fabric over the transom. Apply carpet tape to the upper edge of the reap iece of wood and press it against the fabric. Trim the excess using a straight edge and razor cutter.

Finished, ready for motor.