Wouldn't it be easier to take thumbnail generation away from the artist and have it the same as other sites where the thumb is auto generated by the system and then have the nudity tag apply to thumbs as well as the image!!
I mean, can't be that difficult 'cos it already generates a thumb if you can't be arsed doing it yourself!!
Other sites use this system, C3D for one, RDNA [I think] for another!!

Injustice will be avenged.
Cofiwch Dryweryn.