Longlining is a skill I never acquired, but always admired.
20 years ago, I flew as the panel-monitoring sandbag in a 212, while placing the letters "AMP" on top of the Centrepoint Tower in Sydney, 1000' up. No references at all anywhere near our height, he did it all looking down the 100' line via the left-side bubble. I was amazed at the rapid and large cyclic movements, though the aircraft itself moved position very little, apart from the attitude changes with cyclic.