If you want to bring the pipe to the ground, an alternative is to use some wall brackets.
http://www.antennapartsoutlet.com/Pa...allMounts.html I would secure the mast at the level where the pipes nest and at the eave peak. Holding 3' of the mast below the peak rigidly should be fine, and then the mast would extend 7' above the roof peak. I'd use 3 pieces of top rail and set the bottom one in your pad, at the height that puts the top pipe at 7' above the peak.
Just an alternative, that uses the ground anchor.