Scale sunrise, set,

I really like this - just what I need! Thank you.
It would be great if the sun rise, set, arc indicator that overlays the map could be scalable to span greater distances.
I'm plotting sunrise across Austin, vantage points to view sunrise/set over specific landmarks are miles apart. The arms indicating sunrise/set will not extend from specified point to another location when map is enlarged...or am i missing a feature you already have? if you how do i do this?
Thanks again!