If you do take the north shore, there are many enticing possibilities:

Petite Rivière Saint François: Pretty village on the St. Lawrence River at the end of a wild 5 km descent on a road with 8%, 10%, 11% and 15% grades! Several reasonable B+Bs. Not sure about camping.

Baie St. Paul: A bit touristy, but a nice place to stop for a celebratory meal. I stayed at an inexpensive B+B right in the middle of town, and gorged on ice cream and local cheeses. Lots of art galleries, if you like that sort of thing. (I actually bought paintings and had them shipped home.) In Baie St. Paul, I took a geological bus tour to view the remains of a meteorite that gouged out this area a few hundred million years ago. (It was offered in French only when I was there.)

Isle-aux-Coudres: A picturesque island in the St. Lawrence with very few hills, accessible by free ferry. As you descend toward the dock at Saint-Joseph-de-la-Rive, the hills have grades of 18% or even 20%. The views of the river and sky and mountains will take your breath away. (And not just from the sudden change in altitude!) I really struggled to climb these hills after spending a day on the island, but it was worth the effort.

I hope that gets you started. I am so-o-o tempted to return.