Rear Cab Wall Carpet

OK so I have been trying to wrap my head around how to best insulate/sound deaden the rear cab panel/bp pillars.

I have had several ideas to cover up any sound deadening material which range from a interior matching custom leather panel ($200ish), to kydex (also $200ish), to just covering it with the behind the seat storage I am going to build hopefully this winter(probably about $150ish). The other option is these carpet panels($55) from LMC. They are listed as an option for 87+ trucks. Does anyone know how these attached from the factory? Held in place by trim?

They're held in place by the metal trim rail below the rear window, and by the B-pillar trim panels on either side.

As another option if you haven't already applied the sound deadening sheets, I thought the dense foam mats looked really good as is. They are black and I don't know about painting them though.