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

Forget the reflective stuff. Its made with metal foil and heats up. Go with a fabric shade material that is 95% blockage and you will still be able to see out, mounted on the exterior. The object is to stop the heat before it gets to the glass. Magna Shade is an exelent product but quite pricy. If you are a DIY person you can make your own, copying the Mana Shade design for about 1/3 the price. The most expensive part is the magnets.