Scale the sphere down, till it looks ok. Then hide everything in your world. Do a renderworld, don't clear the z-buffer (cameraclsmode), then unhide world, hide skysphere, and do a render.
Shouldn't be any more intensive, because your rendering the same amount of stuff, and you don't need to worry about stuff poking out or through the skysphere , because, it will always be at the back :)
Shouldn't be any more intensive, because your rendering the same amount of stuff, and you don't need to worry about stuff poking out or through the skysphere , because, it will always be at the back :)