Your truck has a little "black box" on the motor just like a jet...
When it goes in for service, he gets a readout of EVERYTHING
Your mileage, fuel consumption, manifold pressure, idle time, speed, etc. etc.
nothin you can do about it. Its all computer generated
If you need to idle the truck to get rest or to be safe on the road, then it is what it is. If he doesnt have it set up with an AC unit on the sleeper bunk, then he has to accomodate you
He is sitting at home in an air-conditioned house and working out of an air conditioned office...or, if he also drives, he's not gonna freeze his ass off or swelter in the heat anymore than you are
There isn't any other reason to leave a truck idling other than to run air .. basically
You shouldnt have to worry about it. If there is a policy about idling, and it says that you absolutely cannot do it... what do you do when its in the triple digits outside?
I dont know anyone who idles just to idle and burn fuel....unless thats the only way you can sleep even in perfect weather. That could be an issue....