The utilities earth is on the opposite side of the house, so the shortest route would be up from the ground to underneath the kitchen roof, along the kitchen and up the side of the house, over the roof and down to the earth tube. I don't like this idea much as I feel the wire might possibly pick up RF from the dipole or long wire antenna which will be mounted some 12ft above the roof line.
To this point, I would recommend keeping the bonding conductor to service entrance at or below grade, even if it is not as direct. This way, with bare conductors you do gain some additional "earthing". Best to distribute some ground rods along the way. There have been some reports of building damage due to lightning steam/whatever, so some folks recommend at least a meter distance from the structure. I've also heard to follow the drip line of the roof to increase soil conductivity. You will hear lots of things!