A few related questions:

1) Would that limit you to a single 'champion' unit or could you have several different ones? So, if you had five different captains (or generals) with their bodyguards could each captain have a different skin or would they all have to be the Achilles model?

2) How many differentiated models can you have within a unit? Say you wanted Achilles favourite 'friend' Patroculus beside him, or the LOTR mod wanted to do the twelve fellowship within a single unit? You could presumably reskin the captain and the standard bearer, but could you go further?

3) On the topic of unit sizes, and I may have totally gone off the deep-end on this one, small elephant units have only three members (though more riders). If you could reduce the size of the riders to be near invisible and replace the elephant model with a human model could we then have a unit of three?