In an ideal world, the footage of Rebels and other cartoons could be used, but the change in style is simply too jarring to pull that off. Same with most Video games, which is sad that it is too different to use.
I’d say EA’s Battlefront is close enough, so long as you don’t see any faces. Then again, the same could be said about CG Tarkin. If Tarkin is passable, maybe we just ignore the same slight offness in the Battlefront faces and use footage from that. It would provide at least 2 hours worth of content to fill the otherwise jarring gap between RotJ and TFA.
Clone wars arcs???