Oh…Corsaire with your mylar sheets. Try on the inside of the windows. We use just like a curtain and put up and down. But you could “attach” the thin [fairly fragile] sheets to the inside of the glass. Cut to fit inside the window framing for easiest result. Then get a water spray bottle. Spray the glass all over LIGHTLY. Not water running down. Then pat the mylar to the dampened window. It should stick for a while. Might have to spray to stick again. Just with water, mind you. Can be removed and put up again if necessary. We’ve found it really cuts down on the sun’s heat but you can see thru it….darkly.
This also works if you’re using large bubble wrap sheets. Spray water and they stick.
OldMtWoman