In the year the mod is set, the Tribunal is also fighting Dagoth Ur in the first campaigns (2E 882-3E 417) to retake the dwemer forts around Red Mountain and the Cult of the Sixth House starts recruiting through dream-suggestions but before the Cult sets up bases outside of the mountain (3E 400). It would be neat if you included that in some small way. Maybe have special "looters" that are blighted creatures and ash monsters. Creating an entire faction for House Dagoth might be overboard though.
And by overboard, I mean awesome.
And by overboard, I mean awesome.