Or, Cryptic could do something similar as they did with their "monster" system in City of Heroes. That is, the NPC's have no level, but instead are always a set amount of levels above the player. For Player A might be level 10, and Player B might be level 30, but the level difference for the same creature would be the same.

Another alternative would be limits by ship class too. That way perhaps a higher ranked character actually enjoyed those fleet battles, and could still participate in a Miranda just like everyone else there.

The problem with the limits by class or ship type is that they make no sense for a universe "at war".