Just me 2 cents worth. If you planning on doing it youself, metal sheets can be ordered in any length you want. However if your roof come to a single point, there will be a lot of cutting involved, unlike a standard 2 sided roof. Like Johnbacon mentioned, snow brakes or cleats are a must before any roof protrusions like chimneys, antenaes etc. Once the snow releases, it comes down fast and hard, wiping out anything in its path. (Don't ask how I know this ). Nice to have them over the entrance too, if you use the camp during the winter. Once the snow falls it packs down pretty hard.
...Scotty