Matt....seems u have 18 players interested. No need to exclude anyone.
2 leagues of 5 and 2 leagues of players.
4-player league = 6 games in total (round-robin). That is 6 x 10 mins = 60 mins.
5-player League = 10 games in total. That is 10 x 10 mins = 100 mins.
Run these side-by-side on 2 tables
Then top 2 from each group into Q/Finals = 4 games on 2 tables = 20 mins
S/Finals (best of 3) = 30 mins max
Final (best of 3) = 30 mins max.
4 hours MAXIMUM and this can be cut down if you only have best of one at the end if time is tight.
Some games wont last 10 mins either.
Also, doing it this way, the 5-man groups can be cut to 4 if you have no-shows.
I dont mind running it for you if you wish. Just seems a shame to limit it to 1`6 players when it is easy to get around it.
If you can only get one table then run it as 2 knockout sections of 9 with top 2 from each meeting up in the semi finals( also easy to run
)
Hope this is of help.