Just stumbled on you site. Have enjoyed reading through some of it.
I have a 2006 Westfalia with about 50,000 miles on it.
Just thought I'd jump in to say that in the Owner's Manual of the "Dodge" Sprinter, there is a note about not running the air conditioner for long periods of time with the engine at idle. No, the amount of time is not defined.
I feel that I must advise that the Westy does have the five cylinder diesel engine. Also, the air conditioner (roof mount) is a Kerstner 12 volt
unit. The power for this is provided by the engine alternator, generator (via converter), or a/c shore power (via converter). There are some really massive electrical cables running from the engine bay back to the batteries and to the converter. The batteries will not power the air conditioner.
I think that the load placed on the alternator and engine at idle be sufficient to potentially cause some over heating of both the engine, and more so, the alternator in some conditions.
While on a trip a couple of years ago, I ran into a fellow who used his Westy as a portable office, and ran his air conditioner while stationary for extended periods of time. He replaced his engine a good bit earlier than I would care to.
Just as a point of interest, my Westy is the only one that I, or John Hudle know of, which has been retrofitted with a diesel generator, 3.0 PowerTech unit. It hangs down too low for Airstream to have ventured into installing it. Although I have to be very careful about angle of attack when entering driveways, and looking closely at objects, the conversion has served me well. Not quite two years ago, Paducah had one heck of an ice storm. I was without power in my home for about twelve days. Fortunately, I had a full load of diesel on board, about 27 gallons. My puppy dog and I spent twelve quality days in the rig. I had power, heat (Westy has a diesel furnace which is wonderful.), cellphone, satellite TV, and all the comforts of home. Couldn't have left if I wanted to. Had good layer of ice on my driveway going up to highway at the front of my lot.
More than you wanted to know, but hope some of it is useful.