Just came back from a 2 hour hwy drive and surprisingly the rear trunk wasn't hot at all, not even warm. When I opened the trunk it felt just very, very slightly warm, but after a couple of seconds the heat dissipated and was the same as ambient. Air temp is/was 58. I was driving the posted speed limit.
Maybe the 987 has different heat shielding?
Anyways, just my 2bits to the thread.
Cheers