You don't say exactly where in Southern PA you are, or by what route you plan to go towards home.

I agree with the suggestions of Mason Dixon (Gettysburg), and Evergreen Farms (Huntingdon Co.).

There is also Kreider Farms in Manheim. they have planned tours, but that may not be what you are looking for.

Franklin Co. (Chambersburg, PA) is a big dairy county, but we don't have any dairies close in size to Mason-Dixon or Evergreen.  The biggest one we would have would be Mercer Vu Farms (Rod Hissong).  Rod is also current president of PDMP - Professional Dairy Managers of PA. 

There are a couple of robots in Franklin Co. (and I think Mason Dixon might have robots as well ??  I could be wrong on that.)

Post again, and let us know your general gameplan.