Hello Russell,
I can help with very minimal not much but I think this can add some value.
ITALIAN VAT is quite complicated, it has VAT books and the section into each topic.
Means if say example for Sales invoice, you need create a section and add that section into the VAT books.
And, most interestingly, there are pages in each settlement period, which must be sequential for each month.
I can suggest one thing- in your demo environment, just play with the book creation and all, it will give some idea.
I am sorry, when I left my last company I could not retrieve the setup I did there.
I would expect some other expert add some extra value in detail, which I could not.