After looking closely at the locations of all of the scratches on that bra, and learning that 99.99% of them were right at the back of the tank... I decided to install a genuine Honda tank pad instead.
In the U.K. this pad carries part number 08P61-MCS-800 and is shown in the official Honda U.K. Accessories Catalog as an accessory tank pad for the CBR1100XX, ST1300, and a few other models.
In the United States the part number is 08P61-MCS-100 and the box says that it's an ST1300 part.
Bottom line is that it costs $40.14 from Ron Ayers and it fits the XX very well.