[Alneyan]

Can't you just make a design call for a Small Transport with a Colony module? I have been told one wily AI in TDM builds Light Cruisers with Colony modules and weapons, so it should be possible to do just that... then again, I know nothing about AIs (except how to cook 'em: they are quite tasty with a drop of red whine).

Colony Ships are sleek looking though (at least under the few shipsets I use), and it might be easier to find them when you have 758 planets and approximatively two thousand vessels. You should still give your Colony ships clear name though: mixing up those Rock, Ice and Gas colonisers is the perfect recipe for absolutely wonderful headaches.