How can I create masks for the "Draw Lines" and "Draw Text" nodes in the "OnPaint" event?

In the image below, notice the 5 sided diamond shape in the top center. In the center of the heading ticker tape. The ticker tape “under” this slides to the left and right. The center diamond is fixed in position and displays the text of the current heading. I’m drawing this in the “OnPaint” event of a Widget Blueprint. The inside of the green shapes is black with a 0.5 alpha blend, so the terrain rendering beneath it can still be seen. So I can’t just paint over it in black. I do not want the ticker tape below it to render inside that diamond. Is it possible to create a mask to prohibit the Draw nodes from drawing in that region? Is it possible to just erase the region after the Draw nodes to draw the ticker have executed? If there is a totally different way to accomplish the same thing, I’m open to suggestions.