A friend of mine had a hex-beam on a 40 foot telescoping mast for several years without problems.
He used a medium duty Hygain rotator to rotate the entire structure (rotated the entire mast with the antenna on top) without any problems.
He did use a thrust bearing to remove the vertical weight from the rotator.
The rotator and thrust bearing were mounted on a 4X4 wooden post, with about 2 feet of the post in the ground with quickrete.
He basically copied what is described on this site:
http://www.hex-beam.com/the-mast/His post was not as tall as the one in the article (I believe his was an 8 foot post overall length)
Guy wires are certainly needed for anything over 30 feet. Below that, it depends how much wind load or side load you have on the mast but I recommend guying to prevent bending of the mast.
A word of caution - slight bends in the mast will result in the telescoping sections getting in a bind (not being able to lower or raise the mast).