I could post a bit of Velcro with some really good double sided tape on it, I did this for the secondhand gsa tankbag I bought, the part with Velcro on mine has a metal hook a couple of inches wide which attaches under the rear of the tank, since fitting i have never bothered to remove the zipped part from my bike, it doesn't bother me that its on show all the time, anyway if you want a bit send me a pm with your address.
