I have done this on a number of windows and it works really well. My windows are smaller, though, which makes it easier. I just tacked the acrylic up using very small cable clips, meaning to go back and do it properly with magnetic tape, but it works so well as it is that I have never revisited the installed ones and do a couple more windows each year. (...and yes, UK based, in Northern Scotland with 80 year-old single-glazed windows and plenty of weather!).