I''m going to embark on a hiking trip across Canada. (see
The Canada Experience) i would love to use a bivy sack and hammock the entire way. Given Canada''s extreme conditions in the winter do you think this would be possible? Can i get a reliable four season bivy and hammock, or will i need a tent? If you know of any specific products that you would recommend please let me know.
If you are talking about middle of winter, particularly up north north, you're probably not going to want to be hammocking. I hammock a lot in canada, and I get into "shoulder season" down to about -15C at the very coldest. I've camped down to -35 but only on the ground, and you will be warmer there.
Now having said that, I think you should really plan your trip around avoiding winter - or break it into sections where winter bits can be done in populated areas. You'll have a very hard time doing winter in northern Alberta/BC/Yukon if you are taking the northern route on that trail.