We put together a light box with two low energy bulbs in it, to provide plenty of light inside the shower! It was made of spare pieces of our fermacell boards to make a box, with aluminium foil glued onto the inside surfaces, to reflect as much light as possible downwards. The light switch is mounted outside high up on the cubicle.
We also fitted an air duct from the cubicle to the main ducting to provide some extraction of the steam and heat, to draw in fresh air, as the whole cubicle is one sealed box (ceiling and walls all joined together). The fresh air will enter around the door itself! It probably would get hot very quickly and may feel too stuffy! So we thought we had better fit an air extraction point!