Breony
I like Erizon's idea a lot. However, don't make it an "endgame" thing, make it a major part of the game for all the players.
On one hand, I completely agree. In fact, outpost battles work this way: everyone can contribute in some way, large or small. However, like outpost battles, a max-level opponent would mow down a LOT of people who weren't close to max level without much difficulty.
But then...
Breony
It would be nice to actually see Kitins have some kind of agenda (one we could interfere with), instead of just scuttling around aimlessly.
This could be where lower-level players could have more of an impact. The closest thing to what you describe that I've seen in the game so far is the Kitin Patrol. Mostly, they just have a large aggro radius and wander around higher-level PR areas, on patrol.
If, during certain phases of the overall battle, the Kitin had to send out messengers to various other colonies, or perhaps scouts looking for resources or potential victims, they could be level-appropriate for the zone they're in. The NPCs in the capital cities could have a link to the patrol/scout existence, and offer missions to kill them as long as they are still alive. If the Kitin complete their mission, they make gains on the battlefield, maybe receive reinforcements. If you stop them, they don't.
I did intend that the crafting/construction/destruction part be suitable for non-max-level players.