I think what Lenny is getting at here is that you could create the gasline map in Tableau and export it as an image which could then be utilized as a background image rather than a regular map.
I'm not sure of any other way to get disparate data of this sort on a common map except potentially using Mapbox. Check out some of the Datablick views with multiple layers using Mapbox and Tableau here: http://datablick.com/blog/
The synchronize zooming idea is not one I have found for multiple maps in the same dashboard. You could add this as an Ideas.