>>1175302one of these fits nicely behind the stern seat in my canoe, but pack so you are just slightly stern heavy. big jugs of water also work great for ballast, you can place them in the bow for solo paddling, and depending on your source, dump the water for portaging and fill it again at the next lake / river stretch.
the 5gallon jerry can easily holds enough water for 2 people over 5 days. though that also depends on the person and their water discipline, a couple summers ago I went car camping with a girl who went through 2 of these over 3 days, I hand never seen someone use so much water. if you are going through towns or staying in camp sites you can fill up along the way and lighten your load.
soft bladders are nice and light, they also compact down when empty but more prone to puncture and leak, so chose what you think fit's your needs.
also on a side note, aluminum gunwales like in
>>1175245 really start to sting your hands when you smack them and it's cold. I much prefer vinyl gunwales. Mahogany gunwales on a ceder / canvas canoe is the dream