Trying to make a "photo rig" need car guy/ fab input

[Matt]

Here's the general idea.
I want to get a photo like this:

or
http://www.wallpapergarage.com/libra...280x1024_5.jpg

using a setup somewhat like this:
http://www.automotiverigs.com/

I'm drawing blanks on how best to attatch something like this to the bottom of a car. I'd like to make something that can be easily changed up to work on different cars as well. Magnets are out since so many cars are aluminum. And I don't like suction cups much since I worry about hurting the car. I also figure it has to have 3 mounting points to accomidate for pitch and yaw. Plus it all has to be quite rigid.

I have no idea what clamps to use that would work on the most cars.

any ideas guys?