I am with Denelo on this one, no guns, and if possible, with mountable cargo pods so everyone could customize the colours. And make the maneuverability very slow, compared to slowest battleships. Speaking of cargo hold, 8000 really is a lot and it would be a great advantage and everybody would want to fly it.
So what about making the hull/shield half the large train? And maybe even without bots/bats? To compensate the enormous (8000) cargo hold. Then it would really be a fat lure for pirates and escorts would be necesarry...
Oh and it would have to cost a lot, like 100 mils or so...