At our church community garden we need to support a fabric sun shade (18' x 18') made by Cooleroo. One side should be approx 14 feet high and the other 9 feet. According to Cooleroo we need a 4" dia schedule 40 pipe (or a 5 x 5 wooden post) set in concrete 1/3 of its length for adequate support. That would be pipes 21' and 14' set 7' and 5' deep, respectively. Sounds like overkill to me and the cost of materials and erecting this is way out of budget. Do you guys agree with these requirements and do you have any suggestions? The shade cloth would be for seasonal use in central NC.