This sounds like my fat boy Bacon lol. I got him at 8 weeks and he was a little monster, he literally walked with his mouth open trying to grab anything and everything.
He got better at around 3 months n change and then went ballistic again, like something snapped.
Long story short, with plenty of patience and staying consistent with the same techniques you mentioned, he is 7 months now and rarely mouths. Only when heís playing rough and really excited he might go back and start (grabbing my hand) but no bite. Even at that, I calm him down and resume playing without the mouthing.
Be patient and have family and friends be consistent and before you know it, itís gone.
Sent from my iPhone using Tapatalk