I am thinking of getting a Twin Trucker for my Ford Explorer...

I would mount the antennas to the roof rack and run a ground wire since the
racks have a rubber gasket to prevent leaks. I also want to use springs at the
base in case I get some low branches etc.

Will the springs hinder the quality of the signal? If so, is it marginal?
Is the ground wire idea ok?

Rinning a Cobra CB.