Generic CustomEditor

This question borders several previous questions so to be clear: It is not a matter of serialization of generic types, which has been answered elsewhere.

I have a generic class:

 public class EnumeratedPalette<T> : AbstractPalette where T : System.IConvertible
 {

     Color[] colors;

     public static int EnumLength {
         get {
             return System.Enum.GetValues (typeof(T)).Length;
         }
     }

     public static string FieldLabel(int index) {
         return System.Enum.GetName (typeof(T), index);
     }            

     protected void Reset()
     {
         colors = new Color[EnumLength];
     }
 }

And then I make specific versions of it like this:

 public enum FaceColors { Skin, Eye, Hair };

 public class FacePalette : ProcPixel.Fundamentals.EnumeratedPalette<FaceColors> { };

They serialize perfectly and work in unity as expected, getting the right length on colors when added to an GameObject. But instead of having a colors be a simple list in the inspector, I would want a generic CustomEditor for EnumeratedPalette so that I can set nice labels on the property-drawers based on the specific enum ( Color is a struct of mine with its own CustomPropertyDrawer which draws whatever label sent to it):

 [CustomEditor(typeof(EnumeratedPalette<>), true)]
 public class EnumeratedPaletteEditor<T> : Editor where T: System.IConvertible
 {
     public override void OnInspectorGUI ()
     {
         
         int size = EnumeratedPalette<T>.EnumLength;
         for (int index = 0; index < size; index++) {
             EditorGUILayout.PropertyField (serializedObject.FindProperty ("colors").GetArrayElementAtIndex (index), new GUIContent(EnumeratedPalette<T>.FieldLabel (index)));
         }
     }
 }

Edit / Workaround solution

I made a generic helper class:

 public static class EnumEditorHelper<T> where T: System.IConvertible
 {

     public static void UnpackProperty(SerializedProperty prop)
     {
         
         int size = EnumeratedPalette<T>.EnumLength;
         for (int index = 0; index < size; index++) {
             EditorGUILayout.PropertyField (prop.GetArrayElementAtIndex (index), new GUIContent(EnumeratedPalette<T>.FieldLabel (index)));
         }
     }
 }

And then each CustomEditor can look like:

 [CustomEditor(typeof(FacePalette), false)]
 public class FacePaletteEditor : Editor {

     public override void OnInspectorGUI ()
     {
         
         EditorGUI.indentLevel += 1;
         EnumEditorHelper<FaceColors>.UnpackProperty(serializedObject.FindProperty("colors"));

         EditorGUI.indentLevel -= 1;

         serializedObject.ApplyModifiedProperties ();
     }
 }