lighted logo through plexiglass

In your case I like your first Idea better, based soly on the reason that generally speaking, the inside of fiberglass enclosures arent parlicularlly pretty. I mean you can spend the nessasary time to smooth out the entire inside just like the out side, but you are putting in a ton of time into the inside of the box then. Concave is harder to sand than convex as well so you will put more time into the inside than you will the outside. I would stick with your first plan with the paint or I would make the box completly fiberglass and then build a  wood trim ring into the box with a wood backing behind the frame. I would then smooth the entire thing out with bondo or whatever your choice is and paint the whole damn thing. Then get your plexi piece etched and snap it into the ring. Use led's sunk into the sides of the wooden frame to fire light across the plexi as opposed to under neath it. What its gonna do for you is light up the edge of the plexi and the Logo in the center and leave the rest clear which will just show through to the wooden back of the tray that you painted the same as the box. If done right it could look pretty cool and its something thats not quite as run of the mill. Plexi windows to the inside of the box are over done IMO. Bandpass kinda turned everyone on to them and now I can go buy a box with a window inside for like 30 bucks from the outlet shop and thats with a driver. I dont want anything I build to look even remotly close to something I can buy for 30 bucks.

What I have done is make the window in the niddle of the box like you would normaly do and then make the plexi glass go all the way to the edge of the box. So that it covers the entire back of the box. Thjis way it is much easier to hide the edges when it is at the edge of a box.

Also Marian text is what I use to bond things. It is expensive (like $70-90 a quart) but well worth it.