I'll be boringly conformist and agree Ventura stuff is the best option for carrying contraband on the back of your bike.
Have you ever seen the results of a badly fitted tail pack that slips into the rear wheel? Not nice at all
and Ducati's, especially anything with a single seat are not overly endowed with good bungee points.
I also think rucksacks are garbage for long journeys, unless you have a very fit French bird perched on your pillion seat with the largest possible rucksack on her back. French ladeez seem to cope remarkably well with this form of torture at 150mph
