There are two very low-tech ways you can do this.
1. You can change the "Scratch Space" - in Preferences/Display - to a higher value on the left side, e.g. 500pt+. (You won't see it change until you create/open a different document, and this will look odd when using a layout that isn't single sided.)
2. You can change the size of your main window to only accommodate the visible document and move the window to the centre of the screen.
Neither of these is particularly good or "right" but they do the job as I understand your requirements.