
Lol jackbox, your pup sounds like my last 3 Briard pups, my current one is nearly 6 months old. It is not funny when they emulate the wall of death and you are the target. But you are right, they do get older very quickly and you find yourself missing the mad behaviour sometimes.
I find that my pup still does this at night and will probably continue to until he is at least a year old, my breed take several years to become half sensible, full sensibility never happens, even when they are seniors. The Peter Pans of the dog world!
Redirecting has helped us. We take a few favourite "special" toys, ones that he doesn't have access to unless I give them to him, and then put them in his mouth when he is biting us. The more fuss and noise we make the more he thinks its fun and ignoring just gets your back bitten and scratched. These are his "lounge" toys and he only gets them when he is being sensible and allowed in but in these circumstances, I make an exception as he really does relish and enjoy these toys. He runs about with them shaking his head and "killing" them, pouncing on them and growling. I did try some training with all of mine when they were in this mood but quickly found that they were not in the right mental state for learning. I allow him to go wild with these and if he still continues to use us as his teething testers, he is then put in his crate with a tripe stick or other favourite chew toy, (a kong is good, I stuff these with various food stuffs and then freeze so they have to work at getting it out) until he calms down. It also gives us time to recover as if we are feeling a bit stressed by it all, he very quickly picks up on it, one seems to feed off the other I find.
A good pup training class sounds like it will really help you but try to find one that is recommended by someone who has been to the one that you are considering