I guess it would also depend on the camera you are using.
If its a large bulky Camcorder, then you run the risk of the weight and vibration causing it to fall. You will not only break the camera but piss off the other racers from the debris.

Here is a cheap mount, but not sure if i would trust it.
Chase Cam 3 Suction Cup Mount - eBay (item 300243448305 end time Aug-18-08 18:46:26 PDT)
If your heart is set on getting that outside shot, then i would highly recommend a "bullet" style camera connected to a solid-state recorder. This would help you with the problem you indicated with controlling the video, while keeping the main components safe.
The Bullet Camera is designed to give you flexibility in mounting.
Ive seen "kits" listed for around $400. DVR + Camera + Cables, battery, mount, etc . . .
Like this one that i have owned. Not the greatest resolution, but its easy to use and mount.
Sony 480 line Color CCD Bullet Helmet Camera 30G DVR - eBay (item 330258717171 end time Aug-13-08 07:44:48 PDT)
My favorite is Archos Video Recorder with the optional Helmet Camera accessory
ARCHOS
Personaly, ive had my cameras mounted on the dash, on the roof outside, and just behind the drivers seat - best camera angle was over my shoulder. Great view of the field, you can see your steering inputs, and if fortunate enough you can even see the speed and rpm.