For the OP, there is actually a gym in center city Philly that has some bumpers. It's called Rittenhouse Fitness and it's at 20th and Rittenhouse. I wouldn't get too excited though-- there are no platforms or dedicated space of any kind for doing bar work, so you're going to have to be very mindful of other people working out in the in the free weight area (which is pretty small). They also have signs up about dropping weights, so you may need to make do without being able to work heavy.
Also, from what I hear you don't need a car to get to the facility in Moorestown. You should be able to find an NJ transit bus downtown that will take you to a stop right outside the club in about 20 minutes. If you can get the bus once or twice a week, and train the rest of the time at Rittenhouse you should get plenty of good work in.