Could you add a flag (either in the "Fog" command or in the "Skydome"/"Skybox" commands) to avoid that the fog affects the sky.
Something like this:
Fog(RGB(0,188,200),10,20,2000[,#PB_SkyNotAffected])
In the current PB version, as soon as you add some fog, you can't see the sky anymore (=> no "clouds + slight blue fog for the depth cue"

Thanks