Gee, a lot of tears here. The ice and water shield / dam is important for condensation. In commercial construction we do a lot of metal panels for skins. Granted they are not subjected to the same forces as in the vehicle, but the principle would be the same. Pink insulation works very well. We use both -- pink insulation on the metal stud cavities, and foam / backing board to metal sheeting in metal panels. I think the assembly R-value is over 17 or 19.

One thing I have found useful on doors will electric window mechanisms is undercoat spray. In my last van, it actually reduced the road-noise to a point that road-noise from glass overcame it. The undercoat spray also helps with heat insulation of course. It will stink for a while, but it shall come to pass.