Inzil, I would agree with some of the things you say about Sauron's relation to the Orcs etc., but then, Aragorn was a person who has been traveling a lot, even more than Gandalf, to "Rhun and Harad (!)". I think if anybody knew by what names Sauron was called all over the world and in different cultures, it was him. Also, the idea that Sauron "does not permit his name to be spelt or spoken" must have had a good reason behind it - I mean, people must have had a good reason to believe it. Probably some proofs. And actually it seems far more likely that the experiences with the usage of Sauron's name for the Free Peoples would come from Sauron's emissaries rather than from the actual denizens of Mordor - after all, if there was any contact with Mordorians, it was more likely in the form of encountering emissaries (or in the form of combat, of course). And so, one can imagine that if encounters of this kind led people to believe that Sauron does not allow his servants to use his name, well, then it certainly must have been true. (Another way to learn this - and a reason to learn this - would have been when sending spies among Sauron's men to gather information for the West, and for such a spy not to give himself away it was essential to know that he should not use Sauron's name, as otherwise everybody would know that he is not a real servant of Sauron.)
And as for self-declaration, how about using the good, old title "Lord of the Rings"? I can't think of anything more fitting.
(as he could not yet use the title "Lord of Middle-Earth")