Never had a bike fugged with.
But,I have a little free time before I ride so I'll go all CSI on you.
Detective
Sargent Rubb thinks:
The impact did not come from a downward or upward angle.
The force came at that helpless,minding its own business, tail lite from an' angle parallel to the ground the bike was parked on.
Your crime scene photo shows indications of blunt force trauma being inflicted from a right-handed perp situated to the rear of the vehicle facing the vehicles left side.(the impact is left of center,on the lens).The angle of the "weapon" delivered its deadly blow,not from above or below,we are looking for a perp of average height. It is hard to determine the exact weapon used but the spread pattern of the induced fracture suggests it was very localized as seen in Exhibit "1". A windshield injury is shown for reference.
Exhibit "1"
...then again the previous owner could have backed the bike up into something...and you just noticed it now. How the fug do I know,I'm just some shmuck who's seen to many TV shows and drank 3 cups of coffee.
Put an' ad up in Classifieds/Wanted...maybe somebody who has changed out their tail section will have what you need.IE: Gixxer 1K tail swap. Drag racer with aftermarket tail.Perhaps somebody like me who foolishly went with a hard-to-see smoked out lens. Regretfully,I don't have the goods you require.
Rubb.