The vehicle modification that I had really expected to see by now is the straight up cargo pod. An attachment that increases the Encumbrance Capacity of a ship (and thus increases it interior size). After all, an XS freighter is just a YT-1300 with a large cargo pod mounted to it's port docking ring, and a YT-1930 is one with two small pods mounted on the back. The many unique configurations of a Nebulon B is just a multitude of different pods mounted on spars.
There could even be different types of "utility pods" available for vehicles. A cargo pod to increase Encumbrance Capacity, a passenger pod to increase Passenger Capacity (perhaps with a luxury version that costs the same, but increases it by less), and for larger vessels a "facilities pod" that increases the Consumbales by having cafeterias, freshers, and water and sewerage tanks.
I would have thought that this would be a given for Fly Casual or Stay on Target. However if the Consular-Class Cruiser is going to be introduced in Desperate Allies, it could be introduced there and be an integral system of that ship.

