Here's a picture of a rig I made my buddy years ago for him to run a video camera in a helicopter. He just strapped it in the seat next to him. Make the "U" shaped piece under the camera out of 1/4" steel to increase the mass of the camera. The frame is SCH 40 1.5" PVC. For the suspension, simply use bungies. You'll have to wrap them tightly to keep the camera from wallowing and nodding. It's just a matter of experimenting until you find the combination that works. To tighten up the bungies, simply wrap more turns around the frame. Drill a 1/4" hole in the bottom of the mount and use the tripod mount hole in the camera to secure it. This makes it easy to remove and to operate the controls.
Maybe some version of this will work for you.
It was just quicker to hand draw it than to fool with Autocad...
