Roof rack for kayak

I would advise against putting J racks on the factory bar.  As previously mentioned, get some thule (or yakima if they make it) adapters and put a real crossbar attached to your rails.  Then you can go with something like 70+ inches wide and put them straight to the bar and/or add a J cradle if need be.  Factory cross bars are not safe for hauling more than 1 boat, and not even that if you're going highway speeds IMO.

Newer factory bars are well rated. My 1999 had a 65 lb capacity my 2009 has 165 lb capacity same model car. I had two boats on my old one and it was scary new one doesn't budge. More than two boats or if you want a hullivator style factory is out.