Thanks to all of you for your responses. Your advice quickly settled the sleeping bag issue: my husband will bring his 20F bag. And after reading your suggestions and doing a lot of additional research, we did decide to go with one portage pack and one backpack (with dry sacks inside).

The other ...

My husband and I have a 7-night IR canoe trip coming up at the end July/early August. We've done shorter canoe overnights but this will be our longest trip, and first trip period on IR. Most of our gear is ready, but we still have a couple of questions.

We were planning on using two 65L backpacks ...