LED and plexi on the doors

after learning ALOT from this forum as well as glassmans DVD's i will be attempting to do some fiberglass doors on my car and want to incorporate some designs that will be lit up by LEDs. my question is how would i go about doing this? read plan below and post comments please 

my plan: lay mat on top of the current door and resin it, then cut out design and add plexi behind the cutout from the backside of the door. drill small holes into plexi that are big enough to house an LED. ive heard scuffin up the plexi makes for a better lighting effect....is this true? also so you cant see the ugly insides of the door through the clear plexi i plan to spray paint the back side of the plexi black....would this help or hurt the light difractionthrough the plexi?