
I dont know what you are allowed to use to show your dog on, but the leash I use is a martingale leash. Also, I place it high on the neck. Then the head doesnt go down, and if it does, sometimes without resistance from the dog, you can hold it up by having a tighter leash. Had this problem with Cher when she was younger, always wanting to sniff the ground. Now, she doesnt put her head to the ground.
Yes, you can practice a bit to much. I had a friend tell me to put my dogs on the table for 3 hours straight, and that it would get them table trained. Well, I didnt do it, I thought it was excessive. I just trained her at meal times with half her ration of kibble and I didnt go to show classes with her. But if I work her just before she gets into the ring, she is bored with it. So I dont do anything on the day of the show.
HTH