Theoretically, if you put one extension ladder on each side, and had two guys of basically equal weight going up them at the same time, you could simply change the pulley from the ladders.
I would make sure the feet are of the ladders are flipped up, and pressed into the soil. And, tie the ladders off on both sides of the pole at the top.
You could even fab up something attach to the top of one, or both of the ladders to hold them in place at the top.