Glad to hear that the extension worked well for you. I'm not sure if it could help, but using some of the lightweight folding plastic sawhorses to set the canoe on next to the car before you lift it up might help. Since you've got a wagon, you could probably even just store them in the back of the car so that they're always handy when you need them. Also, you've probably already realized this, but be careful about loading it when the wind is blowing. Even the biggest of men could be blown over if a gust catches the inside of a canoe held overhead.
I noticed your comment about the bugs not being out yet, which I'm sure is a temporary situation. I discovered and used a product that covers that problem as well as another. The product is called Smartshield and its a combination of sunblock and an all natural insect repellent. http://www.smartshield.com/detail.aspx?ID=26
I honestly kind of wished it didn't work so well because I think $9 is pretty expensive, but I have been proven wrong. It performs both functions quite well and also will not damage flylines. (I have no vested interest in the product, just like telling folks about DEET alternatives.)