OEM Aprilia Accessories Pannier Bags Kit - AF1-2S001764
This official Aprilia accessory gives you some touring capability for your Tuono.
Includes all parts required to mount the LH and RH semi rigid cases seen in the image.
Aprilia does not note the bag dimensions nor capacity, but we expect these to be in the neighborhood of 20 to 25 liters per bag.
Aprilia was careful to note that this set up is only guaranteed to fit with the stock exhuast, but it looks to us like most aftermarket exhausts will allow installation, though some very short pipes will be much more likely to soot or even burn the bottom of the RH bag
Installation instructions in .pdf format