What if we used a two-tiered CEV? A CEV applied to a small, hand selected group of moral philosophers could be used to determine weighting rules and ad hoc exceptions to the CEV that runs on all of humanity to determine the utility function of the FAI.

Then when the CEV encounters the trillion Dr Evil uploads, it will consult what the group of moral philosophers would have wanted to handle it if "they knew more, thought faster, were more the people we wished we were, had grown up farther together", which would be be something like weight them together as one person.