Ability to designate a "Top Layer" when setting dumping/leveling designations.

Currently, it feels rather clunky if you want to have an area filled out quickly, but also have the top be soil for trees, farms, or just aesthetics.
You either have to have two mine towers, one set to dump your 'underfill' (usually stuff like Waste and Rock), and a second one to dump your soil, and when the underfill is done you have to mess with the areas to stop dumping Waste and Rock and start dumping Soil, and then you have to place your dumping designations again
Or you have to do the same thing, but with a single tower, tell it to stop dumping Waste and Rock and start dumping Soil, and again you have to update your dumping designations.