>>10616811>>10616832Make a kitchen foil sunblind for your window(s), use plenty of duct tape and overlap sheets to make a relatively robust square that you can stick up then take down again. Have this up whenever the window is in direct sun, when it should also be closed with curtains / blinds drawn. You can get also get infrared window film that you permanently stick to the glass, this creates a sort of one-way mirror effect where if it's brighter outside you can see out but other people can't really see in. I recommend getting this as well, but it's a bit expensive, can be tricky to put up by yourself without ending up with bubbles / creases, and doesn't cut the heat as much as kitchen foil does.
