Other things you could do (if your network supports the modes):
1) limit the channel on a rolling timer so that it reset the limit every so often..... (example: //timerLIMIT 0 180 //mode #channel +l $!calc($nick(#channel,0,a) + 5) <-- I BELIEVE that would evaluate on the timer fire and NOT the timer SET)
2) set a join limit so that X nicknames in Y seconds can join
3) make the channel invite only
4) make the channel only registered nicknames can join
Those are some other ideas IF YOUR NETWORK supports those modes
