Our former stick-built home had a window like that BESIDE the door...facing west. In Arizona. You can imagine the results....
What I did was to find a piece of cardboard and cut it carefully to fit the size of that window. Because the window had a pretty stained-glass pattern that we wanted to show off, I covered the cardboard with white Con-Tact paper. It kept the sun out perfectly, and the stained glass showed up much better than before, so it beautified the exterior, as well.
In our current MH, I adapted that technique for our kitchen window. We're night owls, so I don't like people being able to see that we're up at night...and who wants heavy drapes on a kitchen window!
So I again cut cardboard to fit, only this time I covered it with DARK Con-Tact paper. When we put it up, the most-used room in our house looks totally dark from outside!
Easier, cheaper, and more effective than curtains.