Suggestion:
Dump all players in the city siege queue.
All of em. No matter if the person is solo/grouped, has even numbers, or any semblance of balanced archtype into a new scenario type. Name it something funnier/wittier referring to "Siege Over." Make a poll or something - who knows, maybe it'll be a good one. Runs the exact same rules as current siege mechanics with the current custom rules:
Renown rewards: yes!
Stage completion tokens: top scenario rewards (up to Oppressor) for either a total domination (8) or total defeat (2) - no royals.
Bag rewards: no
Quitter debuff: does not activate upon leaving
Why?
This suggestion would bring RoR an instanced scenario with good rewards for a win but crap for a defeat to all the players that the Matchmaker System left out.
Stages take a loooong time and not worth 2 tokens for 15 minutes of getting crapped on by the enemy. Does not penalize people to leave a lopsided loss, resulting in no tokens awarded for the end of the stage when everyone on one side quits.
How will it affect the overall oRvR campaign?
Probably not much if at all. At worst players get a long drawn out evenly matched firefight with oddball matchups on both sides. Mostikely it'll be a quick wipe and the losers will all log, resulting in the winners only receiving what they were doing it for: shits and giggles.

I humbly ask that you take this into consideration. For all of us pubbies.