I guess that depends on what the custom fields are, also if you want to also add content ahead of time. What I gave you only covers automatically adding the layouts. If these have repeater fields as well then they would not be shown.
It would be virtually impossible for me to tell you how to get all the fields to display and this is not something that I’m going to build for you.
What you need to do:
1) Create an example post with all the fields you want to be shown automatically and include either the default content or some example content
2) Edit the load_value function to add this at the top of the function echo '<pre>';print_r($value); echo '</pre>'. This will display what the value needs to be set to in your function.
The value may be hidden by CSS, you might need to look at the code of the output page or dig around with a code inspector.
3) Build the array needed to populate your field using the example.
To be honest it seems like a lot of trouble so that someone can avoid learning how to use the interface and not have to click a button to add a row, at least to me.
