Change a variable name only on the Inspector

For sure you can! And it's not that hard!

Create a first script called RenameAttribute.cs and copy paste the following code:

 using UnityEngine;
 
 public class RenameAttribute : PropertyAttribute
 {
     public string NewName { get ; private set; }    
     public RenameAttribute( string name )
     {
         NewName = name ;
     }
 }

Then, create an other script called RenameDrawer. Place this script in a folder called Editor

 using UnityEngine;
 using UnityEditor;
 
 [CustomPropertyDrawer(typeof(RenameAttribute))]
 public class RenameEditor : PropertyDrawer
 {
     public override void OnGUI( Rect position, SerializedProperty property, GUIContent label )
     {
         EditorGUI.PropertyField(position, property, new GUIContent( (attribute as RenameAttribute).NewName ));
     }
 }

Finally, in your original script, add the attribute we've just created:

 [Rename("My super properties!"]
 public TPC_Properties properties;