So, how to integrate Ducati DesertX OEM pannier racks and Perun moto Top luggage rack?
First, remove Perun moto Top luggage rack if you have it installed. Then install OEM pannier racks and check if everything fits well.
When you make sure all fits well, loosen all eight bolts holding the pannier racks. Four per side. Don't remove, just unbolt approx. 10 mm.
And remove rear strut.
Left and right side should be loose enough to move freely 2-3 cm. This should provide enough room to insert 4 mm spacer (or two M8 large washers) between the upper front pannier rack mount and the frame, as shown. Undo the bolts, insert the spacers and reinstall the same bolt. Don't tighten, leave it loose. Do the same on both sides.
Then install Perun moto Top luggage rack. As per instructions for Top luggage rack. Just insert the Perun moto side supports between the frame and upper rear pannier rack mount. Use bolts provided with the Perun moto rack, with 3D washer. Don't tighten up yet, leave it loose.
Now reinstall the rear strut.
Everything should look like this now, photo below.
Tighten up all bolts. Start from the rear strut, then upper pannier rack mounts on both sides, then the lower pannier rack mounts. Check if everything is aligned nicely. Make sure not to cross-thread anywhere. If needed, loosen the bolts and start over.
At the end, install the Perun moto Top luggage rack plate.