Window Tint with Shade Cloth!
I could not tint my rear window with film as it is made from polycarbonate like they use in race cars but 1/4" thick as I have broken a couple of windows when towing my trailers on gravel roads. It has a scratch proof coating on one side but is also available on both and I would recommend it. It worked out to be a 1/4 of the cost of a new window and is un-breakable. With some brands you can't tint as it releases a gas which bubbles the tint so I had to come up with something else. I used shade cloth that you can get at garden supplies and is very cheap as I have enough to do two windows for $5 AUD. which is only $2.50 USD. So you could do all your rear cargo windows for about $5 USD.
First tape the shade cloth to the outside and cut around with scissors 1/4" in from the outside of the rubber moulding. Next start at the bottom corner ( the top when closed ) with the hatch open and the cloth resting on your head and fold double about 3/8" and push with a plastic picnic knife into the fold and push in between the rubber and window.
Once finished with the first edge, close the hatch and work from inside and you have to the same fold but leave a bit of slack in the cloth so when you push it into the moulding it will be tight. Then do the same with the sides and you are done. I have used this for quite a while with great success and pull out one end to clean the window once a year. In the beginning you notice it but after a couple of weeks I don't see it anymore. The photo above is about as bad as it can look with me parked in the shade except with the window in full sun and the camera focused on the cloth and not the fence in the back ground.