I would recommend cleaning your face before going to bed... There are great products out there for water-free cleansing, like makeup removal pads that are pre-soaked with makeup remover. You can hardly mess it up - just swipe & you're done.
Because if you sleep in your makeup, you run the risk of clogging your pores, bacteria entering your eyes (from the eye makeup), and the makeup will also contribute to deepening your wrinkles if it stays on the surface of your skin too long.
Happy camping!