All of the skyboxes from Outerlight's "The Ship: Murder Party" ported directly into TF2. For a list of included skyboxes, check the Sky List on the VDC Wiki.
Also included are recommended light settings, since the ones used in the original game were bad.
Also, heads up! Tropical02 is half the size of the other skyboxes and is incredibly pixelated as a result. If you MUST use it, remake it at an increased size as soon as you can.