Your post makes me wonder if you make sure you have flotation for your packs.
Nothing beats seeing your best camera headed for the bottom of the lake, except maybe seeing your camping gear following it.
After losing a few things in capsizes I started tying everything that would not float to the canoe, or to something else which would float, usually both.
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One friend of mine used to stow a small anchor in his canoe with a fairly short painter line to it, especially on rivers. His idea was that if he capsized it would fall out then snag up and he would be able to recover his canoe and gear instead of seeing it go down the river to the sea.
(It is not a trick for white water where it would likely just drag your canoe under, but I avoid white water for the same reasons you do, in spite of how much fun it can be. [ok, I might run a small chute once in a while instead of lining through or portaging around, but only after a real good scouting of the run, no haystacks, holes, sunkers or falls])
I never did the anchor for just his reason either, but I still tie a rock on a line (killick) and stow it near the bow in case I want to anchor in the stream do do a bit of fishing.
It does not need to be huge to do the job.

Where do you get your pea soup tabs and the tomato bullion cubes?

SCA--yup they will float..i use Duluth packs with heavy plastic bag liners and inside a sleeping mat and two stuff sacks with the sleeping bag and clothes also inside plastic bags..the food and cook gear bag is the same deal.my small day bag with the lunch,water filter,first aid kit,camera in a WP box and so on should float.i know you guys Up North run alot of rivers..Coppermine,Back,Nelson,but in Minnesota and Quetico in Canada it's lots of smaller lakes so the danger level is nill.

Well, I am inspired by this thread to go out and start my own overboard vest....thanks