This is a very interesting question. As you state in your answer, Gol D Roger knew what happened in the Void Century, as did Whitebeard, whom he told, Clover and presumably some of the others on O'hara knew at least a little, and it is very likely that the Gorosei and perhaps some others at the top of the World Government knew.
But it isn't very obvious who else knows. When Rayleigh is asked whether he knows the truth of the Void Century, he replies that they do, but isn't clear who exactly he is talking about. At least he and Roger knew, but it's possible only a few other officers did, and it's also possible that the whole crew knew, meaning Buggy, Shanks, Crocus and a whole load of others. However, I think this is unlikely. The Roger pirates weren't like the Strawhats, Buggy and Shanks were two cabin boys, so it's likely that the crew was pretty large, and if all these pirates knew the truth, then it seems likely that some of it would be out by now.
It doesn't seem likely that the Gorosei have told any others, and neither did Clover, but Whitebeard could easily have told Marco and some of his other trusted sons what Roger told him. Rayleigh was willing to tell the Strawhats, but preferred not to, and had already been pretty impressed by Luffy, I doubt he would have told the secret to anyone else on a whim, as he preferred to keep his head down after the dissolution of his crew.
In summary, the only living person we have confirmed to know the truth behind the Void Century is Rayleigh, but it's strongly implied the Gorosei know, there is a reasonable chance that some other world government leaders, Roger pirates and Whitebeard pirates know, and I would also expect Dragon to know at least some of the truth, as he leads a very powerful organisation fully opposed to the World Government.