If you don't want to pay 50 dollars for a Manfrotto Super Clamp to hold your camera, you can easily make one out of a one-hand clamp from the nearest hardware store. One of the obvious advantages with this is that it can grip around very large things, like a tree trunk. The Super Clamp is limited to 45 millimeters at its widest opening. Another thing that is better on this DIY camera clamp, is that you can fasten it with one hand.
When I was a motorcycle photographer, I often used a Super Clamp to attach a camera to my car so I could take photos of the bikes while they moved. In the car, I had a computer and remote control to immediately see the photos and control the camera. It was a good setup. When I started out, before I had figured out how to attach the camera to the car, I used to have a driver while I lay in the back of the trunk taking the photos manually with the boot open. 🙂
If I were to take those kinds of photos today, I wouldn't use a DSLR camera, but my mobile phone. It would make it both easier, cheaper and more fun.