So...how about a Nikon with Active VR enabled??? That's designed for shooting from a moving platform, with a VR sampling frequency of 1000 hertz, according to Nikon: that should allow you to get down to some very,very slow shutter speeds with almost perfect cancellation of the vibrations. Something like the new 16-35mm f/4 VR-II lens would be the absolute widest lens I can think of that can cover FF or DX. I don't know if you shoot Canon or Nikon or Pentax or what, but I have been able to get some pretty good hand-held shots as slow as 1/3 second with my old 70-200 VR using ACTIVE mode VR, which is a tip I was taught by somebody---the theory being that Active VR is designed for a camera platform that is moving/vibrating, and a creaky human body at 1/3 second hand-holding a telephoto is, in essence, a "moving platform", if you know what I mean.
I'm thinking if you were to use two guy wires, like say stainless steel fishing wire from say the Malin tournament grade #12 wire (.029" thickness) which is 180 pound test, you could paint it with green chroma key paint and it would knock out very easily in post production, and you could use two guy wires to stabilize the pole, or maybe even three wires, one in front, one in the rear, and one over the top of the car's roof...