[Uwon]

You will need the RS rubber fender mouldings (tRE has them) which have a slit in them that fit right into the bottom edges of the rear fenders. Dry fit with some clamps and drill down thru existing holes in fender. I drilled an extra fastening point on the vertical section between the inside of the rear light cavity and the vertical bumperette. Made an aluminum bracket from the licence plate holes to the rear cross member. I reshaped and shortened the stablelizer brackets behind the rear wheels to meet the new bumper/valance.
Looks like you will have a space between the centre section and the lower deck lid sill which can be filled with a rubber molding and/or fiberglass build-up.
Others have made elaborate bracket from the impact shock mounts out and then across the back to the other mount, then built up attachment points inside the bumper. I did not bother.
Hope this helps.
Johan