If you have balls, do it this way. After the ballonist drops the rope, walk up an step on it, effectively "grounding" it under foot. If there is a leakage current along the 100' rope, the voltage drop across the last 1" between ground where you are standing on it will not shock you. Now without removing it from under your shoe, touch it with the back of your hand about 4ft above where you are standing on it.
If there is any leakage current flowing down the rope, the last 4 ft creates a voltage divider with the 35 to 100 ft above you. The drop across the last 4ft will be only 4/100 times the 12KV, or 480V, which if applied to the back of the hand will cause you to involuntarily retract your hand. If no shock, keep your foot on it while pulling it down.