As answered before---Fehling mounts, work with GIVI bags, I would go for E-21 bags as they are top opening.
Makes scooter wide, German stuff is strong, safety approved and bags will be solid, detachable and not wiggle too much.
Ain't cheap---between GIVI top box, bags, rubber bags on passenger seat, plus "tank bag" in front well, a lot of stuff could be hauled.