While doing some floorpan restoration, I decided to install a sheet of aluminum between the trunk area and passenger compartment. Originally there was only a thick piece of cardboard from the factory that hung on a couple of hooks. I have read some comments on the danger of burning fuel entering the passenger compartment during a rearend collision and wanted to do what I could to make this less likely to happen. The gas tank drops into the floor of the trunk and could burst open if damaged, spraying fuel into the trunk area.
The aluminum is held in place by 20 rivets and 3M strip caulk around the edges. The next time I have access to the panel, I will probably install 6 large sheet metal screws for additional security. The aluminum was given to me by a friend and was light but extremely rigid. It would have been easier to install if I could have bent the lower edge a little but it was some sort of alloy that I could not get to bend.
This shows the view of the sheet of aluminum from the trunk. I painted it with a dull black paint so it would blend into the shadows. After this photo, I moved the CD changer from where it is hanging under the package tray and attached it to the aluminum sheet on that area to the left.
This is how the new firewall looked after adding some FatMat sound deadening insulation. I bought 100 sq. ft. of the material for $130 and have plenty left over to do the trunk area when I restore it. I've been in one rearender already and feel more secure with something besides cardboard between me and the gas tank.