Interesting question. As I have stated many time I am no fan of the Dometic or Heki foe the reasons of excessive heat damage as you state as well as many others. I agree that placing tint on the inside will retain heat- it would not be too much different from putting a physical piece of insulation or reflectex on the inside.
I had to replace one of my Dometic windows. It had the shipping film on the outside to help prevent scratches during transport. It is that standard plastic that we are familiar with for this type of protection. I left mine on to protect the window from scratches when off roading... it has held up pretty well!
...might it be possible to find out what this protective film is and find a similar product that is applied on the outside that is Dometic safe but only tinted?
