OTOH, maybe I'm straying into "realism" here, and should start looking nervously 'round for tar & feathers...?
Well, yeah. From a gameplay point of view, the colony pod does one thing, and so it should be one part. Likewise, a Stellar Converter does one thing, and should be one part. Sure, there would probably be a lot of different components coming together to make it do that one thing: it would need to be integrated with the ship's power supply, it would need an external mounting, it would need specialized controls and security... but all of that is abstracted into something called a large external slot, just like a colony pod is abstracted into something that fits into a small internal slot.
What I was trying to say is that "conceptually" (i.e. "what is a colony"), it's extraordinarily large and complex. Sure, the Cryonic pod may be (relatively) small; but the "basic" colony -- people, livestock, equipment that they cannot build locally (including starship refueling facilities!) is NOT a "small" something. The fundamental "concept" calls for a small convoy, not a single ship... unless it's an INCREDIBLY vast ship...
I mean, I can see the argument that the "colony pod" is a single "part" that does a single thing. But there's a HUGE amount of abstraction behind the idea of a "productive planet," and a "colony pod" carries ALL that abstraction inherent in it.
I'm not actually arguing that a "colony pod" should be broken out into multiple parts that need multiple slots, only that it's a valid and viable approach. I suppose, if I were
arguing this, I'd be arguing that a "Colony Pod" should be an upgrade to an existing "Outpost," or some such...
My actual assertion is simple: I think a "Colony" should be kept as a larger item. Currently that's done (a bit clumsily) by having a "Colony Ship Hull" that's large/slow/expensive to build, but (as noted) it's easy to design a MUCH smaller/cheaper/faster-to-build "Colony Ship V.2"