I have an IC-7000 in one of my vehicles. I use the LDG IT-100 tuner which is made to work with Icom radios. Pressing the tune button on the IC-7000 causes the tuner to tune..
Products LDG Electronics
I also have a 102" CB whip that I sometimes use with the tuner. It works pretty well on 20 meters up, but for 40 down there's a lot to be desired.
Another thing I do with it is mount the 102" whip on my 46 inch Hustler mast (I have a coupling nut to do this). That gives me a 148" whip. (Just under 13 feet). It works pretty well on 17 meters and up. But, I can't drive with it in place.