Thanks Sol.

I have a solution for the nav lights. I've got some clear green and clear orange paint. I'll just fill the nav lights with clear epoxy and paint over them. I think it'll work.

To be honest, I could have saved myself the trouble with the fibre optics if I'd thought of this earlier. I could've used the light from the white LEDs to light the nav lights and would mean 2 fewer LEDs on the circuit.....  :