We designed our Ducati DesertX Top luggage rack to work perfectly with the various rack-less luggage systems and to be small-ish and low profile. It blends with the bike perfectly.
For many riders that use DesertX as a commuter too, we added a top case compatibility. Givi Monokey and SW-Motech top cases can be installed directly on Perun motoTop luggage rack, without a need for bulky intermediary adapter plates.
More details about the installation of Givi Monokey top cases can be found here, in section II.
However, one thing needs to be noted. As the top case compatibility is just an added feature of our Top luggage rack, and not the main feature, top case sits a bit closer to the rider than it would sit if mounted on the "dedicated" top case carrier, like OEM Ducati tubular top case carrier. Reason for this is that Perun moto Top luggage rack is oriented towards rack-less soft luggage, and it doesn't protrude through back of the bike. This has some benefits - it looks nice and compact, and the weight is more centralized. But it has one downside - there is less room for a pillion. For shorter rides, this is not a problem. But for two-up touring, when the backrest is installed on the top case, it may be a little too tight. Depending on the size of the pillion, of course.