Tappan Zee Bridge and 9 west heading south..

If you're on the "inside route" (e.g., the NJTP/I-95) southbound, you can slide over to I-295 South whenever you get the opportunity. I-295 and the Turnpike (NOT I-95) do indeed parallel most of the way south from around Trenton there. I-95 splits off and crosses into Pennsylvania, and then runs down along the Delaware River and through Philly and Wilmington before it starts to head SSW towards Baltimore. You do NOT want to take I-95 between Trenton and points south. Take the Turnpike or I-295, they both feed right onto the Delaware Memorial Bridge. You'll pay a toll to escape New Jersey. Not sure what an RV and toad would be - normal charge for two axles is $4.00

You could also take the Parkway south and then I-195 west across the state to catch I-295 or the Turnpike.