Yup. I think I'll be ok if I can just get all those pieces out then replace with a single (10") piece of foam seal. I really do NOT want to take apart the interior to fix this.
Quick fix could possibly be to to put a thick layer of foam on the under side of the rear deck where the opening in the trunk is. So it slightly lifts up the deck and closes that gap. Id recommend maybe a 1-1.5" thick piece of foam and wedge it in there tight. so it doesn't move.