In reply to DaveHK:
So my thoughts fwtw. The linked trip report goes in via the Little Nahanni which is a very technical white water river so you either need to have good canoeing skills or the inflatable raft type canoes or both. I remember that Tim Emmett SUP'd it in and here is the video of their run down it:
The trip report doesn't really say where they sourced the inflatables from or how they got their food (which they cooked and dried themselves) and gear up there but my suspicion would be that they were based in North America or had someone on the team in North America as a feel the cost of flying in the food and gear from the UK would be prohibitive. By using the Little Nahanni they could drive in but that is not an option for the South Nahanni proper.
I was in Canada and drove to Fort Simpson and flew in from there but that is on the East side of the national park and not easy to get to from Whitehorse. I'd say that the Watson Lake options would work but any of the outfitters will get you in there.
If you aren't canoeists then an unguided trip on the Nahanni is not recommended. This is one of THE most iconic white water rivers in the world and running the four canyons below Virginia Falls should not be underestimated. It's not overly technical but it is big and you risk serious hypothermia if you go in. Feel free to check put my youtube vid here:
The linked one is a mix of two separate trips to the Nahanni and The Snake but you'll figure out which is the Nahanni and there is a series of 3 separate Nahanni vids if you really want to spend some time on this.
So, if you want to mix the canoeing with the climbing I would fly into Honeymoon lakes and run the river down to the Cirque then stash the canoe gear and hike up into the Cirque (This will take you a good day and is a tough slog by all accounts). Then when you are done climbing, canoe on down to Virginia falls where you can get a flight out. The river between Honeymoon lakes and Virginia Falls only has one small set of class II rapids. Your big challenge will be weight and cost. I suspect that the reason the linked trip report went in from the Little Nahanni is because they could drive there, thus avoiding all of the weight restrictions of a flight in. I think this is why most parties either climb or canoe because doing both is a logistical ball breaker.