Thanks for the recommendation. I've heard Krita is a really solid art program, perhaps I should look into it if any future projects call for a custom skybox construction. Textures in general are a bit of a weak spot of mine, as I often settle for Vertex Painting the things I model and animate in Blender.
What I really want to find is a workflow that lets me do custom textures that also have light emissions for some of the colors and not others.