I will support sudden death format. Keep taking a player out after every 5 minutes (10 vs 10 after 5 mins, 9 vs 9 after 10 mins, etc) and the match will end in no time.
My husband used to be a professional football player and he said this is not a good idea nor even practical due to the high physical demands of the game with little to no stoppage. This would have been considered by FIFA if it was practical. He thinks that penalty kicks after playing and running almost non-stop is really the only alternative to end the game.