You can drive the ground rod your customer wants and connect it to the equipment grounding conductor at the proposed sub-panel or the transmitter. This rod does not need to be bonded to the other electrodes that may be present. See 250.54

Just remember that the earth cannot be used as the return path for ground faults, the sub-panel must have an equipment ground.

Few things are harder to put up with than the annoyance of a good example.