Adding a bunk-end light/fan combo is quite easy to do and provides several benefits including a private reading light at night and better air circulation into the bunk.
These devices can be purchased from your local dealer or even on Amazon.com.
They’re normally plugged into an earphone style jack on a roof light.
You then clip the device to the pole holding up your canvas roof. My fan can be mounted in the horizontal position shown above, or vertically for blowing air straight down.