I have the 260 watt panels (three of them) and they are too big :-) They were free so I went overboard. I plan on reconfiguring and just running one of these panels down the center.
I used a mixture of work racks that came with the van and two Yakima roof racks which I had on my Jeep. The underside supports are what they typically use to support the panels on the roof of residential homes with some modifications I made to attach them to the roof racks.