Put a debug mode button in the inspector and lets you toggle debug mode with alt+d

InspectorHelper.cs

#if UNITY_EDITOR
using System;
using System.Collections;
using System.Collections.Generic;
using System.Reflection;
using UnityEditor;
using UnityEngine;

//UNFORTUNATELY this doesn't work right now because the inspector doesn't get refreshed properly in debug mode
//I'm sure it's fixable but I haven't bothered looking into it yet

[InitializeOnLoad]
public class InspectorHelper
{
    static Type inspectorType;
    static UnityEngine.Object[] inspectorWindows;
    static FieldInfo getModeField; 
    static MethodInfo setModeMethod; 

    static InspectorHelper()
    {
        inspectorType = typeof(Editor).Assembly.GetType("UnityEditor.InspectorWindow");
        inspectorWindows = Resources.FindObjectsOfTypeAll(inspectorType);
        getModeField = inspectorType.GetField("m_InspectorMode", BindingFlags.NonPublic | BindingFlags.Instance);
        setModeMethod = inspectorType.GetMethod("SetMode", BindingFlags.NonPublic | BindingFlags.Instance); 

        Editor.finishedDefaultHeaderGUI += OnFinishedHeader;
    }

    private static void OnFinishedHeader(Editor editor)
    {
        //var buttonStyle = new GUIStyle(GUI.skin.button) {padding = new RectOffset(2, 2, 2, 2) };

        bool isDebug = IsInspectorInDebugMode();

        var icon = isDebug ? EditorGUIUtility.IconContent("DebuggerEnabled") : EditorGUIUtility.IconContent("DebuggerDisabled");

        Rect rect = GUILayoutUtility.GetRect(30, 20);
        GUILayout.Space(-rect.height); // Reclaim the reserved space
        rect.y -= 15f;
        rect.x += 5f;
        rect.width = 30f;

        if(GUI.Button(rect,icon))
        {
            //delay it so we don't redraw the inspector while we're drawing this UI stuff
            EditorApplication.delayCall += ()=>
            {
                isDebug = !isDebug;
                SetInspectorMode(isDebug);
            };
        }

    }
    
    public static bool IsInspectorInDebugMode()
    {
        foreach (var window in inspectorWindows)
        {
            var mode = (InspectorMode) getModeField.GetValue(window);
            if (mode == InspectorMode.Debug) return true;
        }

        return false;
    }

    public static void SetInspectorMode(bool isDebug)
    {
        foreach (EditorWindow window in inspectorWindows)
        {
            var mode = isDebug ? InspectorMode.Debug : InspectorMode.Normal; 
            setModeMethod.Invoke(window, new object[] {mode});   

            window.Repaint();
        }
    }

    [MenuItem("Tools/Toggle Inspector Mode &d")]
    static void ToggleInspectorDebug()
    {
        var isDebug = IsInspectorInDebugMode();

        SetInspectorMode(!isDebug);
    } 
    
    [MenuItem("Tools/Toggle Inspector Lock &e")]
    static void ToggleInspectorLock()
    {
        var inspectorToBeLocked = EditorWindow.mouseOverWindow; 
 
        if (inspectorToBeLocked != null  && inspectorToBeLocked.GetType().Name == "InspectorWindow")
        {
            var propertyInfo = inspectorType.GetProperty("isLocked");
            bool value = (bool)propertyInfo.GetValue(inspectorToBeLocked, null);
            propertyInfo.SetValue(inspectorToBeLocked, !value, null);
                
            inspectorToBeLocked.Repaint();
        }
    }
}
#endif