i see umm, the impala build i did is similar to yours like dead on lol. but my plan is when finished lay like tarp type material around the front/top/sides of the box and filling it up with LOTS of expanding foam. that way in the future if i decide to rip it all out after the box gets pulled out the rest just comes down without leaving stains etc etc and trashing the trunk. its just one of my ideas that i might try but for now its just in my head haha. i figure when the expanding foam expands and drys it will be stiff and keep the tarp tight against the trunk
the show is next month here is the link to the thread, i doubt that i will be done with my build but if i am, then im going if not then i doubt it,
http://www.stevemeadedesigns.com/board/topic/70338-2x-meca-event-fresnoca/
also if your anxious to meter your car you can hit up sactownstang im sure he will let for like a price of a XL pizza haha