As you wouldn't be using this rig at the beam of the canoe(s), rather you would be mounting the canoes closer to bow or stern where they're much narrower. Even with two 36"-wide boats touching at the gunwhales, their centers would be at roughly 36" from one another. Assuming they're overhanging the crossbar by at least a couple of feet, a 58" load bar should be plenty. Thule wouldn't include it if it didn't work for the majority of needs. You would definitely want gunwhale brackets or load stops as well.

As is this will not work to carry two canoes. This comes with a 58" load bar witch will not be wide enough for two canoes as most canoes are 36" wide. By getting a longer load bar you could make this work but you would need to have the Thule Canoe Carrier to see that the boats are secure.