I tried but I just couldn't come to grips with a tank bag. It's in my way, it interferes with refueling and it scratches the tank. I looked at several tail bags but couldn't find one in the size I wanted that would sit securely on the rear rack.
Since I couldn't find what I was looking for I did the next best thing. I bought and modified an Oxford Sports humpback. Very high quality, expandable, backpack straps, the works. British also.
The only problem is it was designed to sit on the rear seat of sport bikes. Soooo, I cut off all the funky straps and came up with this mounting system. All it requires is a piece of sheet aluminum and 4 bolts. To remove/install the bag you just run the zipper all the way around, it's on and off in 20 seconds. It's also incredibly stable at speed.