I have done a self-contained low flow Selway trip. I paddled the AZ Verde alone for five nights at high flows, see:
Hardly a Mirage - Paddling Arizona's Verde River | GORP.com
The gear and food I take are a step up from what I do backpacking and I follow the river regs of carrying out my poo. I even take a few beers, but no cooler.
Securely stowed camp gear is just as effective as having a float bags in saving a canoe in an upset. It's density is much less than water. As stated, you do want to put heavy items in the middle.
An advantage of getting a 14' whitewater canoe is that it can be used for multiday solo or tandem day trips.
Originally Posted by openboat
It can be done, yes, but not like a regular canoe trip where I can load a barge (but also limited to pretty placid water - like Ruby-Horsethief). Whitewater canoes are typically fitted with large bow and stern bags for flotation. Fill the boat with gear and you could become a lead weight. I have done a two-night trip with my WW canoe, and squeezed in a very small amount of gear, but it was the most minimalist trip I've ever done. I wouldn't even run a III with compromised flotation and a lot of gear.