I did something recently like this.. my cardboard one got wet and started to sag in places so i got some 3/4 inch plywood and carpeted to the same color as the trunk carpet. Props to the Hardwood look, not my style but looks good.
I thought your whole trunk was gonna be wood grain when I read the title... Wood kinda looks awkward sitting in the middle of carpet. Props for ya on the effort. I'm just not feeling the look.