You are confusing earth ground with a counter poise..

To establish a counter-poise, the counter-poise needs to be directly beneath the antenna.

Just hooking some braid to the antenna won't do anything.

RF needs lots of MASS - a piece of copper braid does not do this.

Furthermore - a piece of wire 9 feet long would detune the antenna system - since 9 feet is a perfect dipole for 6 meters...

I do not think that the OP is sincere in wanting to do anything since his expectations are unrealistic.

The proper thing to do would be to either fabricate a mount that places the antenna directly on the vehicle, or fabricate a mount that goes beneath the tire that tilts and holds the antenna above the vehicle..

I'm not going to comment about women or the fact that most men's problems revolves around their women not allowing them to do things like this. Sometimes a man needs to grow a set of balls and do what is mechanically / electrically correct as opposed to being politically correct...