Some friends and I recently paddled from Carmacks to Dawson City. The journey takes about 6 days.
It’s a very easy section to do as the current is strong. The river pushes you along at around 6km/hour without even paddling. With some paddling you can push to about a 10 km/hour average speed.
The distance of about 400 kilometres means about 40 hours of sustained paddling at this speed.
Rental places allow you to be dropped off in Carmacks then drop off the canoe and supplies in Dawson City before taking a bus back to Whitehorse.