The closest CGs to Philly are probably the ones in Jackson, NJ (near Six Flags Great Adventure). If you don't have a toad, that can be a bit of a problem. You definitely don't want to be driving a MH around in the city. Public transportation in the city is excellent, provided you can get into the city in the first place. If you can locate a CG (or hotel) that's near one of the regional rail stations, you'll do fine. SEPTA's Regional Rail radiates out from the city like spokes on a wheel. I live just north of Philly, and there really aren't many places to RV around here. Best of luck!