Where to buy the canvas
In Edmonton, you can buy wide canvas from Norseman Tent & Awning -- a joint company with Camper's Village.
Any company that makes outfitter's tents should be able to sell you canvas.
Note that you want uncoated canvas -- no water proofing.
Applying the canvas is tricky. This is how my friend did it when I helped him:
First, he took a section of canvas about 6 ...