I said it before, and I'll say it again:

LWO big maps only, LWB small maps only.
Players then have a choice, the two arenas will have a unique distinction without any change in setup or general gameplay. Squads are more likely to make LWO or LWB their home, depending on their preference, thus helping to balance numbers. The problem of facing an arena with 20 players on a large map right after caps kicks in is eliminated. And of course, never again the same map in both arenas.