I couldn't find a Thule or Yakima roof bag as quickly as I needed one to save my life, unless I wanted to pay $85 shipping. But I found this one made by Lund at Advance Auto Parts. It turns out to be surprizingly well made. Not water-proof, but just "water resistant." Whatever that means
It has a felt bottom, and the zipper goes all the way around both sides and the back. It also withstood 95MPH on the NY Thruway without problems.

 

Jeff, from the pic, it looks like the bag is making contact with the roof. It is going to wear the paint when you are driving. Cross bars will keep the bag/carriers up so that it won't contact the roof while in motion. Saw your pics , trip to the Falls, How did the bag hold up? or should I say the roof contact areas or is there a gap between it and the roof?

 

I was worried about that, but I had to do something right now. Anyway, the felt bottom seems to have worked out really well. No scratches. I'll bet if it was up there for an extended period, it might dull the clearcoat though. I took it off when we got to our hotel, and put it back for the trip home. So it was only on for maybe 4 hours each way.

 

Even with a floppy sack on the roof, your red SS looks hot.