Kriega 10 dry tail bag

This is another way to go; I took a Cortech tank bag and cut the magnetic flaps off (mostly) and I secured it to the top of the seat so the seat removes on/off as it normally would. I ran the passenger grab strap through the flaps of the bag so it down secure, and I shot some small screws through the other part of the flaps into the underside of the seat. Works great for me, and it gives a little lower back/hip support as well.