I usually avoid rt 1 for the reasons already stated by others. especially during tourist season. I do like that route off season, but only from Portsmouth NH northward.
Free camping is rare, but I have stayed at Kittery Trading Post, LLBean, Sanford Walmart( nine miles inland), Amtrak Station in Wells.
Nova Scotia is certainly a more expensive trip, but most rewarding as the coast is not packed with housing.
I have never felt safer on any adventure.
The Cabot trail circles the Province and is a great scenic drive with light traffic by US standards.
A side trip to the northern point and a whale watch cruise with Cyril is worth far more than the $20. fee, just in viewing the rocky cliffs.
Scottish settlement museums are well maintained and a day at one can instill appreciation for our lives today.
The Bay of Fundy is also worth the admission fee IF you are there at low tide.
I have not tried to stealth camp there, but have found a few quiet campgrounds along the way, and several that are weekend getaways for the locals.