Action cams are pretty popular, and I picked up a small HD one (a favorite of RC helicopter groups) for some flight videos. I fabricated several mounts for my RV-4 that should work for a variety of aircraft. They are made from 3/4-inch wide x 1/8-inch thick strap aluminum and 1-3/4-inch suction cups that I found online. Besides the suction cups, the straps have a slight clamping action to help keep the mount tightly attached to the plane. A couple of rivets hold the straps together, and foam and felt strips were added to prevent scratching. The mounts work great, and you can’t beat the price—about $7 each.
This mount attaches to the vertical stabilizer and is held in place with suction cups.