Vibrations.....

Isn't there some way to make some sort of "shims" to completely prevent the battery terminal from coming that close to the oil tank?

My old Kawasaki GPZ1100 had about 3 very thin strips of wood installed on one side of the battery tray area to do just this. They are about 4" X 2.5" and do an excellent job of preventing any side-to-side movement of the battery whatsoever. Maybe you could find one of those little rubber insulator boots for the top of the positive terminal too.