Reflection C# - How to get handle to class several properties deep

I am not new to OOP, but am new to Reflection. I'm sure I'm missing something simple and have experimented for some time before posting.

I have been trying to get access to a field, both get and set, its value. The issue is the field is within property of a class within a property of a class.

The following code gets an existing window and works deeper into the classes until I hit a wall. Ultimately I want to get and set "k_LineHeight" inside of an existing instance of TreeViewGUI.

The following code is heavily annotated. Thank you for taking the time to look at this. In Unity's Mono Debug.Log() is the equivalent of write to the console.

    // Get the assembly
        Assembly asm = typeof(UnityEditor.EditorWindow).Assembly;
        Debug.Log (asm + "\n"); // returns -> UnityEditor, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null

    // Get the Type of SceneHierarchyWindow from 'asm'
        Type wndType = asm.GetType("UnityEditor.SceneHierarchyWindow");
        Debug.Log (wndType + "\n"); // returns -> UnityEditor.SceneHierarchyWindow <- Type

    // 'GetWindow' retrieves the ACTIVE instance of the windows currently open
        EditorWindow wnd = EditorWindow.GetWindow(wndType);
        Debug.Log (wnd + "\n"); // returns -> U (UnityEditor.SceneHierarchyWindow) <- Active Object

    // Retrieves the ACTIVE TreeView class stored in 'treeView' from 'wnd'
        var treeViewVal = wndType.GetProperty("treeView", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(wnd, null);
        Debug.Log (treeViewVal + "\n"); // returns -> UnityEditor.TreeView

    // Retrieves the property 'state' that is (public TreeViewState state { get; set; }) inside of 'treeViewVal'
        var stateVal = treeViewVal.GetType().GetProperty("state").GetValue(treeViewVal, null);
        Debug.Log (stateVal + "\n"); // returns UnityEditor.TreeViewState

    // Retrive the value of the field 'scrollPos' (public Vector2 scrollPos;)  inside of the 'stateVal'
        var v2 = (Vector2)stateVal.GetType ().GetField ("scrollPos").GetValue (stateVal);
        Debug.Log (v2 + "\n"); // returns -> (0.0, 0.0)

    /// ALL OF THE ABOVE WORKS AS EXPECTED THE FOLLOWING IS WHERE IM STUMPED ///

    // Retrieves the property 'gui' that is ( internal class GameObjectTreeViewGUI : TreeViewGUI) inside of 'treeViewVal'
        var guiVal = treeViewVal.GetType().GetProperty("gui").GetValue(treeViewVal, null);
        Debug.Log (guiVal + "\n"); // returns -> UnityEditor.GameObjectTreeViewGUI <- Type but I believe I need the Object

// THIS is where I'm stuck...
    // Should retrieve the value of the field 'k_LineHeight' (protected float k_LineHeight = 16f;) inside of 'TreeViewGUI' the 
        var k_Line = guiVal.GetType().GetField ("k_LineHeight").GetValue (guiVal);
        Debug.Log (k_Line + "\n"); // returns -> NullReferenceException: Object reference not set to an instance of an object       

    // If I attempt to ...
        Type testType = guiVal.GetType ();
        object test = Activator.CreateInstance(testType);
        Debug.Log (test + "\n"); // returns -> Method not found: 'Default constructor not found...ctor() of UnityEditor.GameObjectTreeViewGUI'.