Am I the only one that remembers that if you fling a large object at one of these megaships at hyperdrive velocity, it will instantly explode -- even at full health? Tell someone to find an asteroid, and lock their tractor beam(s) onto it. Then have them warp back and release the asteroid just before they drop out of hyperdrive. The asteroid will continue travelling toward the ship, and if you're lucky, may stay intact long enough have large enough fallout chunks to do fairly signifigant damage to one of the other two Royal Cruisers as well.
Ninja: Potential risk would be fallout chunks slamming into your allied vessels...