You definitely want your grounding conductor shorter than your data cable, if you have to coil the data cable up.
(actually not a bad idea, along with ferrite beads)
You want the lightning shot bonded out before it can get to the equipment. I am not sure how the science works out but that is what works practically.
If lightning is even a possibility you need to follow John's advice. You do not want that fire ball transiting the building. It will be flowing down the outside of that conductor.
I didn't use anything but a long data cable and some ferrites on my weather station and that mast has been hit at least twice with no damage.
Best is if you can optically or RF connect your data, even if the air gap is only an inch or so.
