I have been away for a few days, although I have been working when I can. Since I used only one layer of fiberglass inside the truck, it made it easier to pull it out. After you pull it out, peal off all the tape you can. Now that it is out, I can reinforce it with more layers. So you can see I have started my second layer of fiberglass on the inside of my box. I will say this, I wish I had used the blue painters tape! I used the cheaper regular masking tape and that proved to be a mess! I have sticky crap all over everything! The cheap tape and Texas heat don't mix. I used Goo Gone to get the sticky off of my window and off of the interior of my Hummer, so its' all good now, just wish I didn't have to mess with it. I would have spent the extra money to keep from doing that. In the pictures you will see that Painted the back side a green primer (it is just what I had) just to cover the sticky mess. It worked and you will never see it anyway.
In the pictures you will see there is more tape and tin foil. That is covering the spots I missed while it was in the window. Now that it is out, you will be able to see the thin spots and anywhere you missed. Cover the back side with tin foil to seal the spots and add your second layer of fiberglass. You will need 3 or 4 layers total. You want a strong air tight box, so build it up now while you can. After you start to put in the speaker rings, it will be hard to back fill the weak spots. I have built the rings and after I pull them out off the clamps I will post pics of them.