Gold, Ship Sizes and AI

[Andrés]

I noted that in gold Version, AI will not always use the largest ship size available, but will choose smaller ones many times.
Now AI seems to get good combinations of different sizes, and you'll see a lot of small high-tech ships that were very uncommon before.

AI does not seem to make a new design everytime a related new tech is reached, like before.
And when a new design is made it can go back from a dreadnought and design a destroyer.
Does anyone know how does the AI choose which size to design?

Now how do I force it not to do that?
I'm updating the Ultimate Vehicle Size mod to Gold. The new alternative bitmap in vehicle size works great.
In general this new AI feature seems to work, but it will use small and slow colony ships once larger colony ships are available, and that is a serious disadvantage.
I heard that it is possible to add new design types or to call different sub-types in the Construction_Vehicles file. I already have the AI using two different colony ships (for each planet type) entries in DesignCreation.
How do I make AI use the first one only at the very beginning of the game and use only the second one later?