I spent 2 hours are Lowes, scouting supplies and tools needed for the trunk re-design in my 08 Sedan, including speaker boxes, amp rack, false deck (hinged for the spare tire), and false walls on the aft end of the trunk (right and left, behind the wheel wells).
After going over several ideas, I finally found one to stick with that mixes style with functionality, while allowing to keep the most of my trunk able to be used. I am working on the actual drawings and prints now, and as soon as I get them finished, I will post them in here.
The speaker enclosure is for 2 8" subs, it is so, because, well, that is what I am using, with just a touch over the required air space for the fosgate subs being used. Pretty simple actually, take 2 - 10" x 10" x 9" boxes, spread them to the far ends of the trunk, in between will be a 18" x 8" x a sloped top from 14" to 10" with 2 angled racks.
The trick is that thre will be a removeable cover over the visible ares of the speakers and a framed, cloth covered door over where the amp rack is. With the amps angled to allow for air.
I think it will be an interesting design for the trunk of the sedan. As I build it, I will take some pictures and post them for all to see, just in case someone else wants to use it for some ideas.