Should be fun Ned.
How are you going to make a "Rack" for the truck?
If it were me, I'd weld one up, like I did for my Dad's truck, it went over the entire "shell" (we called them "Canopys") sort of like a roll bar.
I bet you could buy one used somewhere cheaper than you could make one, and you could use a well built one for carrying lumber as well.
Congrats on the new canoe, what color are you going to paint it?
The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.
William Arthur Ward