Well, here's some reading, if you haven't already:

An American Experiment in Anarcho-Capitalism: The Not So Wild, Wild West, by Terry L. Anderson and P. J. Hill

The Not So Wild, Wild West: Property Rights on the Frontier by Terry L. Anderson and Peter J. Hill Reviewed by Edward Stringham

The Culture of Violence in the American West: Myth versus Reality, by Thomas J. DiLorenzo

Although it is not with modern advancements.