We put "the cone" around his neck while he was laying in the back seat, but it probably wasn't necessary at that point. I think he was too far out of it to go for the wound, but who knew.

He's really such a good boy... that cone must be extremely uncomfortable, he can't even lick his front paws, but he doesn't fight it. He stands in front of me and turns his head to the side, but he lets me put it back on when necessary. I give him as much cone-free time as I can, but I don't dare turn my back on him for long. He likes to put things in his mouth and it would only be a matter of time before he reaches back there.
I guess this is called resting comfortably in dog world.

Each day I become more confident that the cone won't come off during the night, so I sleep better. Donna checked on him at 2:30 (which I didn't know at the time) and I checked at 6 and everything was cool.
He doesn't seem to have mobility problems but he does limp if he tries to go into a trot. The vet didn't issue any restrictions so I guess it's up to him to do what he can do.
Another week or so and he should be back to normal.