If you've perused this website I'm sure that you will noticed that I have a thing for Thule (pronounced ‘Toolay’), not only are their products dependable, but in my experience they last.
I wanted to fit a roof system for Deux Smurf not because I'm going to be carrying stuff on the roof everyday, rather to carry the canoe around, and maybe the odd pair of ladders.
I ordered Thule’s Rapid System Foot Pack Kit, Ref 754, their fitting kit to suit, Ref 1064 and a pair of WingBars, ref 961.
Fitting them to Deux Smurf was very easy - see here. You don't get written instructions, rather a set of easy to understand images, and if you still don't understand those, Thule have a good set of instructional videos on their website.
The whole system is well thought out and in my experience typical Thule quality. They might be a bit expensive compared to the competition, but I think you get what you pay for, and with Thule you get top quality engineering.