My back window has never been out but I have had the inside trim off, the trim fits pretty snug across the middle 2/3rds but does gap out about the thickness of a nickel at the corners. There is plenty of room for the package tray & insulation, about 1/4". I looked at the OE tray and the jute covers the entire piece except for a couple of notches where the clips went at the very front edge. I'm pretty sure the jute covered the speaker openings. If I recall correctly when I installed the trim without the package tray in place it did not leave room to slide it under but after loosening or removing the lower trim I was able to reinstall the tray/insulation then put the trim on.