Carrying a canoe while towing a TT?

I mount my 17' Grumman standard on roof racks similar to bobndot. For us the biggest problem was raising the 75 lb canoe to the height of the truck roof. I solved the problem by constructing a roller system for the rear roof rack using a length of metal electrical conduit inside a length of PVC pipe. Before hitching the trailer we support the front of the canoe on the raised tail gate while DW supports the back. Then I climb into the truck bed, lift the front of the canoe to the roller. Then we walk the canoe forward until it is centered over the roof racks. Then I remove the roller and secure the canoe to the rack. Centered on the roof, the canoe does not overhang the rear of the truck so hitching the trailer is no problem.