Best way to keep the sun's heat from the front away ?

Hi,

Glass is not magic--but when light hits a surface it changes frequency and becomes heat. Since there are no "perfect" reflectors, quite a bit of light energy becomes heat. Glass is NOT a good transmitter of heat. Remember, too, that light waves of all frequencies will bounce off the surface of the glass. That adds to heat inside the RV if the reflective layer is inside. So it is better to cover the outside of the glass--preferably with an air gap if that can be arranged.