When a ship moves, the lighting does not update and mobs can spawn in it right when you enter a planet. The only way to keep them out is to keep replacing the torches/whatever, which isn't very helpful since when you move again they can spawn again. Plus, if you have a lot of torches, that is a major waste of time. Maybe you could make it so that mobs can't spawn inside of ships?
When a ship moves, the lighting does not update and mobs can spawn in it right when you enter a planet. The only way to keep them out is to keep replacing the torches/whatever, which isn't very helpful since when you move again they can spawn again. Plus, if you have a lot of torches, that is a major waste of time. Maybe you could make it so that mobs can't spawn inside of ships?