When going to Millersburg from Harrisburg follow the roads along the river. GPS will try and send you over the mountain. From Harrisburg it is Rt 22, stay straight onto S River Rd/ 147. 147 becomes N River Rd. Make a right onto 209, also known as State St. Then a left onto Klinger Rd.
The place is in the middle of nowhere. It is easy in and out with a pickup or straight truck. I wouldn’t want to make a habit of going in there with a 53-foot trailer.