Its the little things that can sometimes deliver extra capability for not a lot of money.
The US company Cen-Tex Aerospace has just had their King Air 350 saddle tanks certified that provide the aircraft with an additional 190 gallons of fuel or a split configuration of 120 gallons and a lockable storage container.
The King Air 350 is of course the base aircraft for many manned ISTAR conversions such as the RAF Shadow R1’s
UPDATE
One of our commenters points out that the Shadow R1’s utilise the 350ER model, which already has saddle tanks.