Set pivot on line

Hi,

I'm attempting to create this shape:

I'm currently using the "Metres" Thickness but I would like to use "Noots" instead and have the shape screen space constant.  However, the line scales at its centre preventing me from aligning the lines correctly.  If I can apply a pivot to the way the line scales in Pixels/Noots mode that would work, or is there another way I could achieve this shape (basically a rectangle with one side stroked).

Thanks, Jake