Create Port that is slightly larger and behind its Node

I would like to create a Node from which the user can create links by dragging. However, I do not want to create separate ports, nor do I not want the user to have to start drag from the body of the Node.
Instead, I want to create a single Port, that is a few pixels larger than the Part that makes the Node, and is behind the Node, such that only a thin part of the Port is visible.

The user can drag from that part to start creating the link from it.

How do I create such functionality.


    myDiagram.nodeTemplate =
      $(go.Node, "Auto",
        $(go.Shape, "RoundedRectangle", { fill: "beige", strokeWidth: 0 },
          { portId: "", fromLinkable: true, toLinkable: true, cursor: "pointer" }),
        $(go.Panel, "Auto",
          $(go.Shape, "RoundedRectangle", { fill: "moccasin" }),
          $(go.TextBlock, { margin: 8, editable: true },
            new go.Binding("text").makeTwoWay())