You do not need to show the perimeter dimensions/details. And with that it should be clear to the person reading the drawing.
You may add additional note stating that outer boundary is for reference only.
Michael Gera wrote:
In the past, I've probably modeled an arbitrary shape with the desired hole pattern in it. That's fine, but when I present them on a .slddrw, it means that some form of perimeter, which does not exist in actuality, is shown.
Make the arbitrary shape larger than the hole placement, then crop your drawing view so the edges don't show. (By the way, I really like the jagged outline option that was introduced with SW2017.)
You might also go the manual route if you don't have to do this often. Right click the outline and select 'hide'.