From what I've read, to use a custom player object you simply need to override the OnServerAddPlayer() in your network manager. As long as [Auto Create Player ☑], most of the Object Creation Flow should be taken care of.
"Failed to spawn server object" client player prefabs not showing up.
Code (CSharp):
- using UnityEngine;
- using UnityEngine.Networking;
- public class MyNetworkManager : NetworkManager {