Hi Christian ,
Hope you are doing good.
Just to let you know that this activity is not supported by SAP 
and hence no official notes are there for this.
Apart from the steps that you mentioned, also go through SAP Note
| > 11692 - Renaming the system ID; |
(is not about instance, but SID, but it will give you a good idea).
You can refer to the following link for the guides to perform the copy:
-> http://service.sap.com/instguides
Hope this helps.
Thank you and have a nice day!
_____________
Kind Regards,
Hemanth