If AAF is active when your character is created it is possible to keep them nude until they put on their vault suit. Either get them to dance or indulge in a bit of action with their other half and make a save before their clothes come back. I usually leave the game and then reload (I have problems with Save and Load getting disabled otherwise). 

Reload the game and they should still be nude and stay that way until they put on their vault suit. 

The images below are the best fly on the wall documentary style from the underground Boston newspaper 'Boston Private Occurrences'. Their slogan 'if its private and sensational we'll try and publish it'.