My trusty Hein Gerike bags which I still use have a hole in the bottom on the left hand side following my ride down to Breganze for the "50th" birthday in 97 on my SFC with the 2/1.Ha Dave they look pretty close to the muffler, used to read about bags catching fire. They must be clear but the pic doesn't show it. Love the idea of the alloy plate, I am always doing similar, nothing stays standard with me very long.
As for bin bags, use heavy duty garden type bags.
Paul