Heading south a very good alternate is I95 to RT 9 north at Old Saybrook to RT 66 to I691 to I84 to I684 to the Tappan Zee. This might seem like a long way around but it cuts out all that traffic on I95 south of New Haven. We use this route all the time. 2X on the Cape May Ferry then work your way to Chesapeake Bay Bridge tunnel. I haven't been down the New Jersey coast during the summer so some research might be wise. 2X on the Assateague Islands. Great spot.
We stayed at the Seashores Campsites in Cape May, which we liked, Castaways RV Resort in Berlin Maryland which was OK, (lots and lots of traffic on route 1 south of Dewey Beach toward Ocean City Md.)
2x on the Cape Hatteras KOA. Coming back I work my way to I81 and avoid all the big cities, especially DC. Got hung up south of DC for 4 hours once, never again. Enjoy..