Has anyone considered turning one dragon against another maybe by the summoning shout or maybe frenzy?
It would be command creature/humanoid spell effect because that would give you a better chance of success (frenzy is good for an initially neutral/friendly NPC but it wears off, whereas command magic converts a hostile to the player faction so that both another hostile NPC and the converted NPC see the other as hostile and engage combat, which then continues after the spell wears off), and Todd confirmed that one dragon was more than enough (they apparently removed the random encounter with 3 dragons, which is a great shame in my opinion)
In principal, I like the idea though.