I haven't been to the Camden venue in a few years but what we did was park in Philly and take the ferry across the river to that amphitheater. Then after the show you catch the ferry back and drive home from Philly down I-95. Once we did the parking on the Jersey side and that turned out to be a colossal cock-up getting out of there. Just don't do it that way. Park on the PA side, take the ferry, and return home to DC from the PA side.