The prohibition against idling seems to be a east coast/west coast thing, in other words states where the greenies hang out. Here in Mississippi I doubt anyone could care less if you left your truck idling or not. Diesels lean out to about 85:1 air/fuel mixture when idling, they burn very little fuel idling. In the winter at least, you probably use more fuel starting and warming the thing than you would leaving it idling for an hour or so. It's a classic case of a solution in search of a problem. I know many parts of the country are that way, but I don't hang out in places where I have to worry about someone stealing my truck as soon as I turn my back. Leaving a vehicle parked and idling just isn't a big deal to me, and I don't want to live in a place where it would be.
My current dogs don't usually ride with me, but I used to have an old dachshund that went everywhere with me, he loved to ride in the truck. I always left the truck idling with the air conditioner blasting in hot weather (10 months out of the year down here) when he was with me. I had two sets of keys and I'd lock him inside taking the set with the fob with me. I'd come back and he'd be curled up asleep & snoring with the truck about 60 degrees inside. He passed 5 years ago and I still miss him riding with me. I have two more great dachshunds now, but they haven't gotten into the truck riding lifestyle like the older one did.