[SANDYSAND]

Are you for real? Why you even ask this question here?
You should had done your homework before getting into a dog, he dosent deserve to be in a muzzle for that long period of time...If your clients are more important and your dog is not behaving maybe you should try to train him if you dont have the time maybe you should consider offering him to a more deserving home where is to be the dog he is!
Excessive restraint becomes a test of wills and you will find dogs to be stubborn and not give up. The more you attempt to restrain them, the harder they resist and the less pleasant and more dangerous the experience becomes for all. Best of Luck to the puppy!