I don't think adding a 2D background should be necessary. Sort of makes the skylab irrelevant, doesn't it? Haze is good, but (a) it should be possible to operate on the sky without affecting the scene overmuch, and (b) the haze should be scalable. If you import a human figure at the basic Bryce default of height=40.96, and then add a house scaled to match the figure, even with haze at a very low setting the far end of the house will be showing colour change. It would be very nice if you could say, "Right! 40 units = 2m" and Bryce would then scale all atmospheric effect appropriately. Even better, add a tree, type in scale height of 6m, and Bryce would scale the tree accordingly to the global scale that you had defined.