I sell a mouth blown air horn called the Ferocious Shock Locator that lights them up. It has extended several slow day hunts for us. Locating from the road after fly down with this won't make him start to head to the road.
We used to use a call to locate from the road side but,have learned that method often had the bird heading for the truck after setting up.
Also we have found the toms' will often shock gobble at farther distances with the horn than the rest of the locators. We still carry traditional locators and use them when the hunt calls for them.