I have more cameras than I care to admit looking out double pane windows. If they’re just sitting there, take a fat construction size Sharpie and make them black. Hang dark drapes behind them. Have the glass as clean as humanly possible. Outside screens are not the end of the world - they make a ghost grid that’s usually easy to ignore and detections will still work.
And yes, make shadow boxes - buy on Amazon, or make them yourself following the wisdom of genius fabricator @victormaletic