Thanks Ben! I modified the 'getMarkerIcon' function and was able to get it working with uploaded images. It's a bit rudimentary at the moment since I was just trying to get it working, but basically I just added an if statement into the function to with and indexOf to see if the value in the icon field has a '.png', then call L.icon. I'll likely add attribute fields to the flexible_styles table before it's all over with. Thanks again!

if(returnIcon.indexOf('.png') > -1){

  returnMarker = L.icon({

  shadowAnchor: [14, 48],

  shadowSize: [48, 48],

  shadowUrl: 'marker-shadow.png',

  popupAnchor: [5, -45],

  iconAnchor: [14, 48],

  iconUrl: returnIcon

  });

  }

  else{

  returnMarker = L.MakiMarkers.icon({

  icon: returnIcon,

  color: returnColor,

  size: returnSize

  });

  }