Best ways to keep RV cool inside in desert climate

For those using the Reflectix on the window, are they dual pane? I wondered what the added heat and expanding air between the panes would do to the dual pane window seals.

I've heard of people having problem using reflective type materials on dual pane windows. I put it on our windshield and it's amazing the heat it keeps out. Just afraid to do the rest.

Just curious