Thanks DWeikert, good read, helpful. It gave me some additional thoughts. I can probably mount the panels nose down, front under the bar, rear over the bar. I think the bar would be over the frame of the panel, not light obscuring. That puts pressure on top of the panels while driving, and I can add a deflector (Yakima offers them). If I point the truck south when parked that puts the panels in a slightly better position for sunshine. It wouldn't always be pointed in the most efficient direction, necessarily, depending on campsite selection. I can see me putting the truck north/south though if having the choice so that there is less direct sunlight through the windows. Hmmm...this seems like a fun experiment.