Be sure to see the boat basin at Alma at low tide AND high tide. Take pictures same views. In NS no trip is complete without a visit to Lunenburg & Peggys Cove. There is a good city CG within easy walking distance of the Lunenburg waterfront. A drive out to Blue Rock is well worth the time. Not sure if Halifax is worth 4 nights but Shubie Park is a decent CG.
We spent 2 months doing the Maritimes last year & never made it to PEI. We did spend a month of that time on NL which was the main destination of the trip. Don't know where the time went.