Not sure if by "no new graphics" you mean the layout of the guild can't change (i.e. it couldn't be made larger).
If that was the case then it kind of limits what could be offered in the max guild to mostly passive benefits, so we'd be talking xp boosts or VoS style boosts to skills. Just offering a flat XP boost to skilling is pretty lame (and not really fitting - none of the other guilds offer xp boosts for skilling).
If the layout of the max guild could be expanded slightly, maybe making it slightly larger in the middle area so you could have 2 skilling stands to the east and west of the banking/ge stand. These could be customisable by the player (like invention machines in the guild), and the player could choose to build (for example) a flatpack bench, an invention bench, maybe even portables-style hotspots via invention components (finally enabling players to make portables without relying on MTX).
It would be nice if there was another skilling porta...