What I've been doing is creating a polyline on a separate layer, then whenever I need to adjust the clip fence, I turn on the layer, adjust the polyline as necessary, and then use the "entity" option to reselect the polyline.
You could also create the polyline on any layer that would normally be on for that view and make the polyline one of your non-printing colors. I happen to use color 45 as one of my non-printing colors. So, whenever I need construction lines or bordering lines or Clip Cube defining lines, I put them on an existing layer that will be on when I need that view and I make that polyline my color 45. It can then remain on and visible to me but it won't print to paper or PDF drawings.
I find this easier and less confusing than creating a whole series of new layers for the poly outlines that I then need to make sure I turn on when I need them.
The only concern with placing the non print line on a usable layer is if you are to xref the drawing (as for a M/E or framing plan) and want the xref another color. Then the noprint color becomes a print color.
I usually place the polyline boundry on a title layer, then I will not need it in the xref version.
