I'd put any full body decoys on the levee in relaxed or feeding type groups, with some "lookers" scattered throughout.
If you want the sweet spot out front for everyone to shoot, place your decoys off the pit/blind corners and back to the bank leaving the middle wide open for a landing hole (same for the back as I understand your location of the pit/fields). Now depending on the wind you can adjust them putting the larger concentration of decoys on the upwind side if you have cross winds. If the wind is to your back (depending on the orientation of the pit as to the driection that would be the front of the pit), expect to shoot out front and put just a few decoys right in front and if it were me, I would "rainbow" the decoys in back to form a pocket for the ducks to work right in over the blind/pit so you can shoot them right overhead as they work the "hole" you created. Do just the opposite if the wind were blowing the opposite direction. Main thing is to place the decoys in "family" groups and have a relaxed looking setting.