Does the cam you are using have a battery or capacitor? If battery, I'd remove the camera on hot summer days. My cams have had capacitors and even during long trips to Florida in August, I never had a problem leaving the cam in the window.
Also, if you decide to leave it in the window I guess you could remove the memory card if you want to try and save the card the extra heat.
Honestly, you don't have many choices. Either remove the cam to use the sunshade or take the chance and just put the shade up with the cam still stuck to the window. If the shade is cheap enough and the cam is mounted where the edge of the shade is, maybe just cut a notch in the shade to fit around the cam.