I'm sure this will be a bit complicated to implement to Manu, I'm not sure if Manu can read the games_mp.log to know if the current match ended before start a new map. But I know that It can read the number of players online.
Here's my suggestion, dynamically map rotation, when the server is online with a few players online...manu will use only small maps to play, when the server is full, will use only big maps eg.
[Dynamic maps rotation]
<Max Players-small>:<maps>,<maps>...
<Max Players-medium>:<maps>,<maps>...
<Max Players-high>:<maps>,<maps>...
5:mp_killhouse,mp_shipment... //this means, if there are online between 0-5 players will only run these maps
14:mp_crash,mp_showdown... //this means, if there are online between 6-14 players will only run these maps
32:mp_pipeline,mp_crossfire... //this means, if there are online between 15-32 players will only run these maps
Of course, manu will read the number of players before starting the new game.
Something similar to be available also for gametypes, for less players only a some gametypes, for many players other gametypes (optionally).