So, after much considering of the constrictions of Halo's engine, we've come to some basic points.
Firstly, the ship will be named Hammer of Justice. I came up with the name (go me) and we may include... a little something... to go with the theme.

Second, the ship will be a frigate bearing a few resemblances to the T & R (due to the fact we found that the early T & R concepts looked awesome, and also good for a smaller ship). Here's one here. (CLICK ME)
Third, due to size constrictions and the fact we want a complete interior in the ship, we've decided on a length of about 500-600 metres, a little longer than the human frigates from Halo 2. This also means the ship will be about 300m wide, so we're working over a fairly big area here. The inside of the ship will likely be based off the T & R architecture, with modular sections to help us speed up the time to make the BSP. The ship will have most or all areas accessible, including:







Another thing we want to do is make the players Elites. The story is that one group is still loyal to the Prophets, and control the ship; the others have sided with the Humans and must take it. They will be most likely "spaceman Elites", since I think we might make the frigate drifiting dead in space, with its gravity and propulsion systems offline and its reactors producing barely enough power to keep the ship's life support and electrical systems online. One hangar bay's shield will be flickering, and either a boarding craft or dropship will be inside, which is Blue team's point of entry and flag base; Red's flag is located in the Control Room. The hangar will be badly damaged, leaving only the other operational (well, as operational as a dead ship's hangar can be). Players will probably not be able to go outside the ship, or maybe only to a certain extent such as a hundred or so metres around it.
I think Reaper's started modelling it, although any help we can get would be great.