its better if its longer than shorter. get a rope strong enough to hold the weight that your putting, but long enough to be comfortable, and short enough to "choke" you. if its too long, tie a knot, or turn it around the pole.
also, try making "practices" to see how strong the wood is, just in case.
i do it in a metal one, that is pretty strongly attached to my wardrobe (coathanger), and a rope around 2 m