easy way to put a twist in the far side
After we exchanged emails, I can see why you have a gap for wind to get between your strap and hull. For the other folks' benefit, Todd is using foam blocks on the cross bars to elevate the hull so it does not contact the roof of his Honda Odyssey.
Using that technique, the twist becomes necessary. To put a twist in the side away from you (the non buckle side), just run the strap over the hull and don't worry about twisting it on the far side. Put a twist in the buckle side before you run the strap through it. Don't tighten it down yet. Go to the other side and simply rotate the strap under the cross bar to achieve the twist. Go back to the buckle side and now cinch it down.