Update:
Took the car to the dealership to have the passenger mirror swapped out (it was making a creaking noise). While I was there I mentioned to my service advisor, "If is anyway someone can help me ID the creaking sound coming from the back and make it go away I would owe you forever!!"
He picked up his desk phone, called over the shop foreman, who asked to take a ride with me. he heard the noise, immediately said, "it's the seals and the trunk mechanism." The tightened a few things lubricated the seals.
Like magic the sounds are gone .... for now ... until I hear them again.
