Longer the lens and wider open the aperture will make focus more critical ..
When the subject is 60 feet away the focus will be less critical till the subject is close by..
So you could start wide -ish.. hopefully with a large stop F11.. F16 if the camera will take it.. and then focus will hold quite a while.. if the subject is running all the better.. I,d pull your own focus.. if it goes soft right at the end its fine and can look pretty good..
If they are going to walk from 60 feet away.. its going to be a very long shot anyway.. and you could get away with breaking it up editing wise by having some handheld walking with the subject.. etc
Or fly in a features focus puller on $2,000 a day :)..