I think we need a proper ref's guide. Get a book together with explanations of different styles of play, structuring adventures and campaigns, how to keep players interesting, adding personal stories, making the grand campaigns about the player characters rather than grinding the players' gears with Grandfather Monologues or Poochies, and running grand scale campaigns over the characters' heads yet still involving the Travellers in the pivotal moments in your settings' history.
Oh. Settings.
Any ref's guide needs to be able to grab the Referee, with ideas on techniques you can use to extract effective games and campaigns out of the major sector books, from the Solomani Rim to the Spinward Marches. There are all those big players, huge polities, major political tensions ... how does the Referee bring that tension down to the Travellers' level? And how can their actions and activities scale up to the setting and campaign?
That does include a referee's guide to creating non-player characters who aren't just banks of stats to be fought and killed, and bosses to be fought and killed in boss level battles.