I don't know of any shuttles from any campgrounds to the field. In fact, I believe there is only one campground in Williamsport. You will probably to park further out (we are staying at Yogi Bear in Milton). The drive isn't bad. The parking is in open fields so your rig could easily be parked. I don't think they charge for parking but I don't remember.
Bring chairs. You can sit in the bleachers but I think it is more fun in the outfield. Or you might try one day in the bleachers and one in the outfield. The last time we were there you cold bring a small cooler with food but no liquids. They will inspect anything you bring. Everything is free except the food so it is a great family outing. Enjoy yourselves!
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