Hello Leif,
I don't have experience with pole construction, but--
I do have experience with yellow cedar piling foundations and yellow cedar ground contact in residential applications.
First, as you probably know, yellow cedar lasts an incredible long time in the ground. Here in Southeast Alaska where the ground is very wet and things rot fast, yellow cedar pilings are generally thought to last a solid hundred years.
Second, an old timer told me a while back told me he wrapped the ground intersection of a piling in copper. A friend recently followed this advice and put two feet of copper below grade and a foot above bedded in Atco roofing tar. As we know, the ground intersection is where rot starts, where there is plenty of water and air. My wife is a mycologist (studies fungus) and assures me rot spores must have both air and water, not just one. There is no such thing as dry rot, only dried rot.
Third, our building department calls for pressure treated or naturally resistant wood, and I have built all sorts of things with yellow cedar as a carpenter and contractor in the last ten years and torn apart sound yellow cedar on the ground.
Finally, consider what treated lumber is: a rot prone wood species, usually second growth (ie. faster rotting), pumped full of chemicals that resist rot by leaching these chemicals. It's only a matter of twenty to thirty years in this climate before the rot moves in.
Yellow cedar is full of natural oils that resist rot, grown naturally into the wood.
As a personal question, Leif, are you by chance Larry Calvin's son?
Hope this helps, and feel free to email or call me if you like, I'm in the member directory.
Zach