I did the round-trip-in-one-day thing once or twice when I was in my 20s and had no money and I don't recommend it at all. Stay in a hotel after the meet, you will be glad you did. I know it's an extra cost but it's better than the alternative. I know the turnpike and/or 80 between Carlisle and Pittsburgh very well my F.I.L. was from Beaver Falls - it's long and boring and not always well lit depending on where you are and at what time.