Forget the courthouse. Yes, it's good, but the saloon is so much better IMO.
Here's the game plan:
Indubitably, some one needs the paralyzer. Either have the 'lucky' player take one for the team or cycle through players. Seems to take too long though. -_-
Don't open the doors to the saloon. Use the trample steam to get up there.
Place the SVU-AS up there as well. If you've got unskilled or inexperienced snipers, play it safe and go with the AN-94. Snipers make it much faster and funner (and it's much safer if you've got skilled snipers).
One part I must stressed is…honestly, don't use the traps. They completely defeats the purpose of the game. You get to round 50 and some of you haven't even breached 1,000 kills. Plus, you've got that 'ANIM ERROR' to worry about.
It's flawless. It's got a great escape at the back of the hallway. It's perfect for 1-4 player (the more, the considerably merrier).
Hope this helped. Courthouse seems to be over rated, as it gets overrun by the mid-30s.