Virginia to Maine

Don't go through Boston tunnels with propane. Best to circumnavigate the Boston area using I-495. And if you do this, it makes more sense to continue up I-87 to the Tappan Zee and take I-684 to I-84 to I-90.

Running up I-95 may seem terrible, but you won't have any height issues, as the trucks go that way, and they are going to make sure that they don't hit any low heights.
It really depends on what you want to do.....sightsee during the trip, or get up to Maine ASAP.

I drive I-95 all the time, from NC to NY and often up to Boston, so I'm familiar with it....and as I said, it may not be scenic, but there are plenty of stops and service areas...and you well seldom be alone on the road.

Best advice is to try and schedule your trip through NYC, to try and a avoid the worst of the traffic....for me, that is after midnight, but before 6:00 inm the morning.

Here's an earlier thread on the same subject.

Starting from Virginia Beach, I would cross the CBBT and go north on route 13 through the DelMarVa Peninsula to join I95 near NJ. I know of no low bridges on these routes.

We went up to Acadia NP last Fall and used route 1 from Portland on north. No low bridge issues.

You can use the Good Sam Trip Planner. It will warn you about low clearances & other issues.

http://www.goodsamclub.com/travel/freetriprouting/

I, personally, would try to avoid I-95 until I got north of Boston.