AA very true they don't hold as much.  The main reason I' pack freeze dried food.  I have found if you turn the external frame pack so the frame is sticking up in the canoe they load and unload much easier.  I tend to strap my pack in the canoe and have found one end of the frame usually slides under the yoke allowing me a better option for strapping it in, fewer scratches in the bottom of the canoe also.
My first trip to the Q we took rented aluminum canoes.  We were able to single portage by sitting the canoe seats on our packs and work the portages as a team.  Heavy but effective.

qp