Hi Chrissy, Can I ask what training you do with Tobie when he is not being walked? It sounds like he needs his brain trained too which can really exhaust a dog. Have you considered clicker training with him? at 7.5 months his still a puppy so yes he is at the bitey stage. Tobie might not like his harness lots of dogs don't so you will have to proceed slowly and gently giving him treats to help him. There is lots of information on harness training on the forum. Definitely do not hit or drag him this will make matters far worse for him and you. I clicker trained my rescue dog to allow me very slowly and over some months to allow me to clean his ears, his teeth and clip his nails. I did not just lift his ears and go straight in to clean them. These things all take time especially with a rescue dog. Do you know anything about Tobie's background?
Fully agree with Helen, Tobie probably needs some additional training and brain work to keep him fully occupied and happy. Do you play retrieving and/or searching games with him in the garden or the house? Most labs love that; it makes them use their brain and is actually much more tiring and satisfying than a walk.
Another recommendation for extra brain training. It really helps with Coco, who is older, but was just as wild (except for the biting) when we took him in 4 month ago. We do clicker training. He can now lie down with a peanut on each paw, until he's told which one he can take. When we got him I couldn't even get him to stop jumping all over me, grabbing his harness/lead, biting our old dog, running over the furniture, etc. etc.
I'm not sure why but my dog doesn't seem to want to play fetch. We have thrown kongs and balls across the yard but he doesn't seem to go after them. Even when we offer him a tug toy he doesn't seem to go for it. Instead, he will randomly pick up household objects and expect us to chase him (which we don't as we don't want to encourage him) and will only want to play tug with inappropriate objects like stolen clothing...