[Droplede]

I'm a big fan of using medium transports for colony ships a little later in the game. As noted, the colony module helps take up the 50% cargo space requirement. The 1/2-price hull makes it cheaper than a light cruiser for maintenance, and I get much more room for extra cargo, extra supply and some defense, too. Only drawback is the 5-engine limit, but at least it's not any slower than a normal colony ship. No modding necessary.