I have paddled in Haida Gwaii on four occasions. Our very first kayaking experience in 1986 was in Gwaii Hanaas with a commercial group. Subsequent trips have covered the area from the South Moresby area up to Moresby Camp and have been of 16 to 18 days duration.
As intermediate paddlers and if you have some experience of wilderness camping I suggest that with careful planning you can have an interesting and worthwhile trip. I would recommend something more than a week even if you stay in the area between Raspberry Cove and Skangwaii ( Anthony Island).
I agree with George about the plentitude of potential camp sites and the reliability of Moresby Explorers. If you would like to talk person to person you can reach me at 778 888 3829.