Perhaps we should rotate the numbers in the league?
Year 1 - 10 teams - 36 league matches no split.
Year 2 - 12 teams - 38 league matches with 6-6 split.
Year 3 - 14 teams - 38 league matches with 7-7 split.
Year 3 - 16 teams - 30 league matches with no split.
Year 4 - 18 teams - 34 league matches with no split.
Year 5 - 20 teams - 38 league matches with no split.
Then go back down the list.....