I'd recommend a long canoe trip in Algonquin park (or somewhere similar nearby if there is something similar nearby) if offline is your goal (though obviously not entirely similar to an ocean crossing in other ways as well).
Yeah, it is. Basically just up to your route planning... I feel like at more than 2 weeks people start going farther north but I think that has more to do with "we can" than there not still being good routes in Algonquin.
I'd probably not recommend more than a week for a first canoe trip anyways.