I don't understand all this DP idling either. I crank up and as soon as the air pressure is built up, I am ready to leave. Depending on how long I have been parked this only takes 2 or 3 minutes.
If engine temp is a concern, you should think about turning on the engine heater for an hour or two. I do this if down in the 40's.
Just as annoying to me is having to listen to the guy with a diesel PU trying to back his 5th wheel or trailer into his spot. I swear, some seems like it takes some an half hour. Same length of time when they get ready to leave at 7 am.