If i don’t want to see the page outline i just make the working page much bigger than i need within design central and then insert the sign substrate, or draw a substrate within that.
The outline you see is just the edge of the page, you can make the page as big as you like.
If you type ctlr + 5 together whilst your substrate is selected you will center it within your workspace.
Or, if you are working on a square or rectangle you can make the page outline the same size as your substrate then surely you wont see the page outline will you?
Unless i misunderstood.
Liam