The following is a mockup of a planet with 4 Carrying Capacity. There is a Terran Commonwealth colony in hex 0201, with 1 Census present (x1 note).

Then, for giggles, here is an uncolonized planet with 7 Carrying Capacity:

Now, taking the detailed planetary surfaces to their logical conclusion, we could also have players roll to apply terrain to each planet that would provide a bonus of some sort. For example, the Hydrosphere climate value would define how many of a planet's hexes are covered in ocean. Of the non-ocean hexes, we can also roll for the presence of terrain (Mountains, Hills, whatever -- this is an area I could use some direction on from old time wargamers, or those with strengths in this area).
Here's that same planet with some sample terrain:

The random LunarCell planet that I created for the background called for 58% water, so I just took 7 Capacity x 58% and rounded to nearest (4 hexes), and then rolled randomly to determine the placement of those ocean hexes. I also decided on a whim to add mountain terrain to hex 0203. Tadaa! Detailed planet!
It is important to note that everyone can still live in the ocean hexes -- they aren't "no man's land." However, if you were an Aquatic species, you could probably fit more people in one or more of those hexes.
If the general consensus is that ocean hexes should be off limits in this optional rule, we can probably get around that by doubling the number of hexes per planet and requiring two contiguous hexes per Census. I just thought that this was simpler.
So, any thoughts on whether this is something to pursue for the Companion or not? Would you ever see yourself wanting to use these sorts of rules?
-Tyrel