They sell insulation fabric at JoAnn's for drapes which would probably help and although your windows sound huge, perhaps some of the plastic that adheres to your windows to shade you. It's not dark enough so you can't see out, but it does stop some of the heat and UV from coming in. You can get it at most RV stores in varying sizes. We used some because the bird ate our blinds and he's right in front of the window. It does a pretty good job and you can't see it unless you miss a spot!