Just thought I'd post some pics of what I'm doing, might be of interest to someone looking for a solution. (Thanks to Snootch for helping out with info!
Step 1: Sound deadening the trunk floor

BlueSkin - Found at local Lansing. Seems like great stuff so far, no smell at all, goes on easy. In the end I decided to buy a 9" roll, and glad i did. anything more would cause even more problems around all the curves in the wheel well.

2 Layers of BlueSkin later. A heat gun helped a lot to reveal all the air bubbles and to also just get it all laid out nicely. Just dont overheat the stuff, it burns right through the top blue layer and you have exposed hot tar -> Not good.
Step 2: Fiberglass Mold
Tools! That mask is a must, trust me.
Mask off the area with multiple overlays.. just to be safe.
Foil + more masking tape = a definite must and a life saver in getting the mold out.
Applying first layer... Resin the surface apply the fiberglass and than saturate it with more resin. Precut all the fiberglass before you mix the resin. (Also I didnt do precise measurements on my resin mixes, but as a rule of thumb i always put a bit too much hardener. It's better if it dries in your tray than having it not try at all with fiberglass in place.. Having said that, dont put too much. I made that mistake when i mixed 8oz of resin, managed to get about 3 sq ft done and than the stuff just became like a rock
While the glass was drying i decided to open up some packages i recieved this week from honk kong

LED Sills! Look even better than I anticipated! Will install once I do my speakers
After about 40 minutes i just pulled out the entire mold. As you see the foil helps a lot as there is nothing holding it behind. (Masking below is just for your own security). One tip.. Start by putting the foil around the edges and mask outside edges to the first layer. From there lay more foil and connect each piece to each other, without touching the first layer. That way.. All you have to do if you didnt have any leaks that is.. Is just tear off outside edge masking tape and effortlessly pull out the mold.

Mold after some cleanup, removed most of the tape and foil.

Test fit! Perfect
-- End of day 1. That was enough for one day. I'm going to apply the second coat tomorrow, i think 2 should be enough for my project.. And start MDF work to build up the structure.