My idea is a bottom hinged deck that way you could open towards the front seats so that I'd still have cargo space if I needed it. Part of the reason of course is to reduce weight, a little less weight means a little faster.
With that in mind I was going to stay away from wood, it's heavy. I think fiberglass with light weight cloth similar to the car's carpet in color with a layer of light weight insulation material for trunk noise reduction and interior temp control.
I've pretty much made up my mind to go ahead with this mod, I'll keep the forum posted on my efforts. A two-seat RL! I love the sound of that!
BeRad