Hey Silverbear I have been following this post with some serious interest. I also would love to create a side car for my bike. I have a different donor if you will. Instead of a canoe have you thought of utilizing a Kayak? The Shape is pretty similar and it might be a little more aerodynamic.
Just a thought and if I will be monitoring your progress diligently. By the way the knowledge you have provided to the noobs like me =) is a major contribution to the motorized bicycle community. So don't think you owe anyone anything. That doesn't mean stop just don't feel like you haven't contributed. Hopefully I can provide some redneck engineering for all the broke folks out there.
Don't forget that with knowledge comes power. You my friend could be considered one of the HE-MEN of the motorized bicycle world. You just have a dog instead of a cat but that's OK.