What you are doing is priceless and I’d do it again.
We did the Cabot Trail on rented hybrids and had no trouble with the hills. Suggest you do some hill work prior to the tour. It’s a very nice scenic tour and ACC does a great job with supporting the riders. Enjoy.
It was a grand time. Loved the mix of trails and over the hills rides. Having to break-down and move camp only every other day was a real nice feature of this tour. Spectacular feeling on the road and views. Description of the trip should not lead participants to think it is all bike paths. I love paths because am very traffic adverse, but the better scenery is often the backroads over hill and dale rather than along old rail lines.
Your chosen routes clearly had scenic and low-traffic advantages.