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This looks like it could work . https://www.rockymountainatvmc.com/parts/tusk-olympus-tank-bag-p
I use a SW-Motech Pro Daypack. It also requires the Pro Tank ring. There are also additional accessories you can add (phone case, lock).The really nice thing about it is that it's not too large, and the connection of the bag to the tank ring is magnetic, at least for positioning. It clamps onto the ring, but the magnets ensure it hooks up easily, property and securely. Removes with a pull of a strap. Great for gassing up and then reattaching quickly and easily.
I use the GIVI tank ring and have a few different bags depending on how large it needs to be for that outing.