Measured my divider...looks to be about 0.090 thick. most likely a nominal of 3/32" originally.
For the insulator, look at the first photo you posted on the inside of the trunk. You can see the foam peeking out around the openings. Apparently it could either be foam or jute. I haven't discovered where or when it transitioned or if it was an either-or thing. My car was a Z87 car and it supposedly had "extra insulation" as part of that option package, but nobody has ever said what that actually is other than the underhood mat and the cowl seals. Maybe the foam was part of that?
An interesting thing I did discover when taking off the foam. There was a round cutout in the middle of the foam at the point close to the rear window. The only thing I can determine is the die to cut the foam was made for the cancelled Vigilite system where there would have been and indicator for the rear lights mounted on the package tray, like the '69's had.
Here's a link to a photo:
http://nastyz28.com/media/1970-z87-p...nderside.7756/
http://nastyz28.com/media/package-tr...ion-hole.7757/