That should support the tent well. The Yakima towers have a very sharp edge on top where the alloy casting goes over the bar. Since you have a very wide tent, this will be in contact with the bottom of the tent. I used to file the edge so it had a softer contour. You can also put a piece of hard plastic or pipe insulation on top of the bars to "fair" them.
One thing I found, if the tent overhangs the roof on the sides a lot you can get a weird end plate air flow and it affected my gas mileage. With the narrower tents I never noticed a difference in fuel consumption. It if is a problem, you might want to tape a couple telltales on the outside edges and see what is happening. Might have to make a couple winglets ;-)