Very nice vacation. Enjoy!
If, like most, you are probably looking at I-95 through New York State. From decades ago experience, I have found that it take just as long in traffic on I-95 as it does going up the NY Thru-way to either Troy NY and crossing into Vermont or up to Rutland VT and crossing to take the northern access into NH. Now, this way is more mountainous, but manageable and a WHOLE lot more scenic. The local Vermonters' will hate me for writing this, but pick up some true VT maple syrup Grade A dark amber OR Grade B. It is hard to find better.
If traveling through MD and NJ, may I suggest Valium?
Anyway, expect toll roads. With a camper, double the fee. Thru-way, NJ Turnpike, NJ Parkway and Bridges leaving NJ too. There are roadways you can take to avoid these tolls... mostly.
Being a good ole southerner, can I ask, are you planning to go "packin" heat? Probably legal in VT, NH and ME with a SC permit, need to check. If so, we can help out with that too.