What do you put across the front to back luggage racks to set a canoe on it and tie it down?
side rail towers
I use these on my existing side rails and am very happy with them. http://www.thule.com/en-US/US/Products/Base-Racks/Feet/450-Crossroad-Railing-Foot-Pack
Hope this helps,
If you have access to Meijer, they have a set of Yakima (4) towers + (2) 58" crossbars on sale for $99. I believe this is a good deal (I just bought one), but being new to paddling (and I don’t bike either) I don’t know the pros/cons of Yakima vs Thule.