I just went through the whole "i need to buy a roof rack" pain and ultimately decided I wouldn't do that.
I bought a swiveling T-post for the trailer hitch, and one of the really thick (3") pool noodles to lay a few inches back from my windshield for it to sit on. Provides about 11' or so of support (15' Chum sticks out 1' in back, about 3' in front). I do my front end with the fender dealies as someone illustrated earlier, and once everything is in place, I use some ratchet straps between the ends of the T post and the cargo net hooks in my trunk (two pieces of mule tape, properly knotted, for anchors just outside the trunk seam) for additional stability. I've driven at highway speeds with and without; with is better. A couple bungie cords hold the end of the canoe to the T post, and a cargo strap behind the rear door pillars goes over the middle. Wish I'd taken pictures when I was out yesterday. Way easier to show that way.
I transported my canoe from Western NY to MD recently with no issues at all... about 300 miles.
I used a similar rig when i lived in LA, but the T post was fixed, not swivelly, and bolted to a plate welded to the back bumper (no 'trailer hitch' wiggle room), and didn't move at all. I just really like how easy the swivel T makes it to load.