Before joining the CF to the RF is made sense to remove the bulkhead and baggage floor to add the soundproofing.
It’s not super fireproof but for that location it’s fine. It would be a pity to not use the existing material.
But first I did a test of the adhesion layer. I put a test piece foam on a test piece of aluminum and let it sit in the sun for multiple hours; the adhesion is super strong and the foam did not come loose:
The pieces go back into the RF but only with cleco’s, no riveting yet, maybe access to the underlying structure is needed in the future.