It sounds like you intend to tour the Maritimes from one base campground. While we might look small on a map the distances can be considerable. As an example its at least 5 hours from Halifax to Sidney Cape Breton.
Once when the ferry was operating I met an older couple from Massachusetts who had left Yarmouth heading to Halifax. They had gotten off the ferry that morning intending to see Peggy's Cove (a must see for tourists) tour Halifax, drive up to Cape Breton to see the Fortress of Louisburg, drive around the Cabot Trail (both also must sees) and then make it back to Yarmouth that night for the ferry home. All that in less than 12 hours.
There are a lot of great things to see and a lot of great campgrounds.
Got some extra time and extra cash? Why not visit Newfoundland? Ferry is EXPENSIVE but sooooo worth it.