Try the PetSafe ultrasonic bark control device they sell at PetSmart (and other pet stores). It takes a 9V battery and it should help to keep barking to a minimum when you aren't there to do it.
It's not very expensive, so it might be worth a shot:
Dog Bark Control: PetSafe Ultrasonic Bark Control System No-Bark Collars
The batteries don't last nearly as long as the packaging says, though. I found you have to change them every couple of weeks.