Brettski, I had a similar thought regarding posts and shifting ice. I have about a 24 ft wide area on one end of the pond that I want to build a cheap good looking bridge. I have tried to find old beams that could span the 24 ft. but was unable to locate. Then I saw a detail somewhere that showed a 24" diameter CPP stood up on end about 6 feet long. This pipe was dug into the ground about 2 ft. with 2 feet of concrete dumped in the bottom. The 6 x 6 post was set on top of the concrete with the remaining 4 feet of the CPP filled with pea gravel. I should note that the pipe ended up 1 foot abobve the waterline in this detail. This was originally a detail used for a boardwalk over a wetland crossing but I don't see why it wouldn't work in this case. It would seem that the CPP and pea gravel would protect the post from any ice concerns. I haven't built it yet, but someday I hope to.

Its not how well you do something,
Its how well you look doing it!