We are having the same problem. With 5 Uromastyx all needing a basking spot between 110 and 120 with a background temp of 100 it gets the main reptile room hot quick. We've been using fans to try and circulate the cooler air from other areas of the house into that room. Plus some of the animals that don't need/like it that hot have been moved to other rooms which are cooler. So the house is kind disorganized right now. lol
As soon as it's too hot in the entire house the bf will turn on the air conditioning and then it's not as bad. We just open up the air vents in that room all the way and still use fans.
It would probably make more sense to put in a window unit but at this point the bf isn't willing to do that. Of course I'm also trying to convince him we don't really need 5 Uro's. lol
I might try the suggestion of the curtains too, we don't worry about the outdoor light since we have so many bulbs on timers. They create plenty of light.
Hope you get it worked out, and let us know what you come up with.