It's considerably more insane because its doubling an existing massive river from northern Saskatchewan up to the exit point for no reason. Particularly in an area where there isn't enough infrastructure to support begin to support such an operation.
Using the same start point you already have the Mackenzie river going to Lake Athabasca. From there you have existing rivers and canals getting you to Lake Winnipeg, albeit somewhat inefficiently and would need expanding to get bigger ships through. Although you might need some locks to be added to get around the dams on Lake Winnipeg.
Making the only real canal section being Winnipeg to Superior, and then you're in the great lakes.
If you want the crazy option, get up to Lake Athabasca then go out through the Peace River to end at Bella Bella Coola, BC. Only have to cross several massive mountain ranges and do the crazy descent from BCs central interior plateau down to the ocean.