3-D Skies in Quick Drive

Does anyone know what file it is that tells TS16 where to pull skies from in Quick Drive scenarios? I'd like to replace some of the default sky textures with better ones, but I'm not sure where to begin. I do have the option for dynamic clouds turned on in the TS16 graphics settings, but the skies in QD remain less impressive than the skies in Standard/Career mode. Any advice?