I too have seen the extended idling from the diesel people. I don't think they truly understand how they work.
Run the A/C to cool of the MH? 99% sure they are plugged in! if not they are equipped with a quiet generator.
Run the heat? again, heat may run off the 12V system, if not, again they are plugged in!
I don't unplug until I`m ready to pull out.
As far as cooling down after an extended run on the highway? getting off the highway and driving into the campground and checking in, the engine and turbo are cooled down. as far as warming up a diesel, best way to warm it up is to drive it! start it up 5 minutes before you leave. that's all it takes. If you say it takes 30minutes to fill your air tanks then you have a problem with the system! get it looked at!