J.F.
i like all the previous suggestions. Do you have any ideas why he bites? is it anger or just a sensory input need maybe? .
whatever the reason, maybe tying an object on string that can go on as a necklace might work; Tell him when the urge to bite comes to bite on the object that is hanging around his neck and that is the ONLY thing he can bite.
you will be redirecting the behavior which is good and afte a while when his need to do that stops you can just remove the object.
have him choose the object too; and give him power of choice; remind him a lot during the day, before going out, before going into a shop that is the expectation. THe best of luck.