Great idea. I think the install should be easier than a car, since a canoe doesn't have as many complex curves. It would make a great display piece.
The main issue I see is the vinyl getting jacked up from normal use (if you're fully wrapping the bottom) - being scraped up on rocks, sand, etc. If this is for a customer, I'd be sure to put in a disclaimer that this kind of damage isn't covered by warranty.
Post pictures when you're finished?