Oddly enough, I came up with a premise for a B5 campaign just about an hour ago. It would be even better if the Babylon 5 model and T´Loth model would be complete. Given what we've got to work with, this campaign would follow pilots aboard the Narn heavy cruiser G'Tock (sp?) seen in S2 "The Fall of Night", S3 "Walkabout" and likely "Shadow Dancing" and perhaps even during S4 "Into the Fire". The missions would take place between "The Fall of Night" and "Walkabout", and follow the ship and its crew as they try to escape the Centauri, find disabled narn ships and try to either repair them or evacuate the remaining crew, and perhaps procure weapons. The latter would even involve shipments of weapons and supplies possibly headed to the Narn homeworld, that G'Kar is organizing. Downsides would be the lack of variety of Narn capital ships. It could also use the narn shuttle model. Also, in "Walkabout" Na'Far (sp?) mentioned the various types of ships they had repaired, including "dreadnaughts". Now, I've never seen any Narn capital ship that could be classified as a dreadnaught, in the series. Do you plan on overlooking that reference, or seeking semi or non-cannon designs to fill this gap?
Anyway, this could act as a demo campaign, until more models get inclued. Once these are however, a much longer campaign could follow the G'Tock from missions spanning the war, to their arrival at B5 at the end of S2, through the events included in the proposed demo campaign (though perhaps expanded further) and (if Shadow/Vorlon vessels get included), even its involvement in the Shadow war.
How's that sound?