I rock a 17 foot Grumman aluminum on my truck. You need two belly straps and a bow line, you don't have to tie off the rear. If you can run two straps from the bow to the front corners of the truck, it'll be more secure than just one strap to the middle.
A couple different companies make special rack mounts and such for canoes, but I wouldn't do that unless you really like spending money for no reason. I chopped up a ten dollar set of yoga blocks to use as padding between the canoe and load bars, but I've stopped using even those - the Thule bars have a rubber sheath that provides all the protection and friction necessary.
My canoe weighs upwards of 70 pounds and I can load it by myself. Line it up behind the truck right side up. Grab the front crossbar with crossed arms, and raise the canoe and flip it over your head in one motion, so it's upsidedown and you're bench pressing it. Now hump the bow up over your rear crossbar, and the rest is cake.