This seems like a difficult case to prove? How do you show that the John Does actually used your specific photos to generate their content? Wouldn't you have to seize their computers and/or online activities?
Leaving aside the obvious points already mentioned, what makes you think these fuckwits will bother to scrub the originals from their systems? You may see a few who do so but the overwhelming majority of the gooner dipshits who pull this crap obsessively save every picture they can from virtually any source possible.