I know there are some plugins that provide this, but I just want the lowest risk approach which is just to add the Google conversion snippet to the checkout success page.

The threads I have found about this are all very old. So I would like to double check.

My understanding is:
1. create a empty file called jscript_google.php
2. Paste in Google provided code into jscript_google.php
3. Save here: /includes/modules/pages/checkout_success/jscript_google.php

Is this right?

Is there a way to test this on a live site without actually placing an order?