I don't think its practical to protect against a direct lightning strike, and you don't have to worry about the transformer effect because the currents are not significant.
If you put gas discharge and mov's between the 3 phases (or after the rectifier, so two wires) between the line and the ground, you have to put them on both ends of the tower. if they are at the base of the tower, you could still potentially have enough difference in voltage at the top of the tower to puncture the wire insulation.
If you run the ground wire with the transmission line back to the house, then when the voltage at the tower's ground rods reach 30,000 volts (30,000 amps through 1 ohm ground resistance) well, now you have that much more current flowing into your house's grounding system.
theoretically if you coil your transmission line into a big enough inductor, you can install the lightning arrestors at both ends of the transmission line.
problem being, that might be practical if you run a 480v wind turbine. also the voltage across the inductor will be as high as say, the 30,000 volts i mentioned. PEX tubing would probably work for that.
it could be broken up into a number of inductors, with gas discharge between each one, connected to their own ground rods.