Thanks! This is what I ended up doing.You want to look for the 3M VHB body tape.
https://www.3m.com/3M/en_US/vhb-tapes-us/
Clean the back side of both the medallion and the area of the decklid where it will positioned. Place rows of tape on the back side of medallion and cut any extensions past the outer edge the medallion (cut it back like about 1/8”). Position, align and press firmly.
You will want to do this in optimum temps, such as 65*+, that’s best temp for tape adhesion tape and for the plastic parts.
If using the 3M VHB, it won’t ever come off again, unless someone really and forcefully tugs at it.