An alternative is using devices to manage the last man standing instead of the round setting.
Either setup then ends up at an end game device which is set to end the round.
You can use player counters for 2 teams or add trackers to deal with more.
How many teams do you want ?
You can also setup the class selectors to keep the players on seperate teams when they press the 1v1 button.
You may also want to disable the 1v1 button if there are more than 2 players…how do want this to happen ?
So yes, I think you can achieve what you want, it may take a few days back and forth in this post to get there.