[lincpimp]

Use mortar. It will not stick very well to the powdercoated legs. When you want it off a few taps with a hammer will break it off. And run a bead of silicone between it and the pole when it has set, to keep the water out. You can also slope the mortar so water naturally runs down the pole then off the mortar. Mortar is also very cheap, one bag should do. I would suggest plaster of paris, but I an not sure how weatherproof it is.