I think a message with just the ID and IFF of the base killer would be reasonable - it would be strange inRP if a base and crew just died like that without a word. Also it would give base owners a much needed sense of security that their base was actually killed and not bugged to death, moreover encourage base pew'ers to only stick to killing bases they ought to be killing ID-wise (dunno if the server records who kills bases, and the admins can get access to this info and sanction accordingly, but that would be great too).