Our group is also planning to paddle the William, but from Hale Lake, at the same time (within a few days).
We are thinking of paddling over to Fond du Lac, less likely to Stony Rapids. Where do you plan to exit?
There's a much briefer write-up (from Hale Lake) in Alister Thomas's Canada's Best Canoe Routes. But there's no way it compares to Laurel's, the most comprehensive I've ever seen on any set of rivers.
There are two recent coffee-table books with extensive coverage of the dunes by Robin and Arlene Karpan; I just got them and am pleased I ordered them.
SK Parks will send you a pamphlet, though likely you have easier access to one. I haven't tried to get permits yet.
Yrs, Allan
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A literal mind is a little mind. If it's not worth doing to excess, it's not worth doing at all. Good enough isn't. None are so blind as those who choose not to see. (AJ)