It makes you laugh that it may dazzle drivers but I can drive this with no problems.
The issue is at night when you are in the car and a road train is coming down the road at you with all their lights on.
Ever imagined what it is like to be inside the reflector of a head lamp? Pull up at an intersection, look to the left and all you can see is traffic from the right?
I worked as a window tinter for 7 years and we had a bloke come in to get his vehicle re-done for that exact reason. He got silver tint fitted in Darwin and then drove to Townsville. It looked good and worked really well, but proved totally impractical once the sun went down as all you could see was the reflection of the inside of the vehicle. It was down right dangerous.
I'd go with a metalised window film, it will reflect the heat, but the make up of the laminates won't be overly reflective. Just a tint film will be coloured plastic and doesn't reflect much heat at all.
To also help in the cargo area, go and grab one of those sun screens that look like silver bubble wrap, trim it to fit the window and hold it place with self adhesive velcro spots. It will cost you bugger all and work like a charm.