Here's a few tips ,or things i figured out about the install and from from others who posted.
1. Yes there will be tons of styrofoam bits everywhere, I did the install with the door mounted and put a sheet over the screen and bits still got in the pod and covered everything within a 25' radius of the pod.
2 I also used a fine tooth blade and made sure it was a long one.
3. I cut from the outside, the blade will wander ,go slow and don't force the corners or it gets worse.
4. After I did the cut out I used a large file to shave down the cut out wanders, and then a 60 grit sandpaper on both the outside fiberglass and inside plastic veneers to fine tune the opening.
5. Large bead of silicone on the frame,which gave me a nice squeeze out bead . And then I carefully cut it off after it dried.
Pretty east install if your handy at all.
rgds John