3ds Max :: Custom Map In Daylight System

When I try and add a custom background map to the MR Physical Sky, the map takes up the whole environment removing the ground and horizon making my model look like is floating in the sky. Before I used to do this and the custom map would just replace the sky texture with my own cloud image. I've attached an image of what I'm trying to get which is basically my own clouds image as the sky but still retain the ground plain the MR Daylight System gives you.