I'm glad that you found something that works for you. I went through a similar trial and error period as we tried to fit a complete AI, and a Revolution on top of our old car.
I ended up buying Yakima Mako saddles which suspend the boat on bit of a cushioned ride, hug the boat evenly all around, and also leave space for the sail to be transported below the boat. Then I mounted the Ama's on top, by strapping them to the ama bars that go across the kayak. Secure, simple, and if I had a better car at the time, it would have been less straps then you see in the picture. The trick was to mount the Ama's on the kayak first, then put get two people to put the boat on the roof.
Your way looks like it's also secure, and that's what matters most!
Here's a picture of my AI on the roof of our old economy car, and a Revolution beside it (which could have easily been another AI) *and yes... I know... this picture has been on this forum at least 10 times now... sorry for those who are sick of seeing it.