Instantiate Prefab from outside Camera view

I'm wondering how I could create Instances of a gameObject (say a sphere for instance) at a random position thats just outside of view from an orthograp$$anonymous$$c camera. I managed to get somet$$anonymous$$ng similar by using the Camera.main.ViewportToWorldPoint and passing a Vector3 such as (0,0,Camera.main.nearClipPlane) w$$anonymous$$ch would get the top left corner (I believe) but t$$anonymous$$s solution only accounts for the corners and not all the edges.

I've spend the last couple of hours trying and searc$$anonymous$$ng to no avail, I'm sure t$$anonymous$$s is pretty simple, Just can't wrap my head around it.