templates editing has not changed in the 3 years I've been using QBO, other than some additional custom text boxes. I make use of all the custom fields and it's still not enough.
Did you try making the font's smaller to save more trees?
You can also try limiting your address + website lines... accountants just need address + business number.
Our invoices are actually quite nice looking and I think the Header thing is kind of what accountant's love to see.
Personally, if I may add more feature requests here, we really need to be able to have more custom columns in our Invoices panel so not all invoices are simply sorted by the Customer Name.
For ex 9852934 Ltd Co does not really help on the QBO panel when you have 10 active invoices.