We tried to do this as a camping trip several times, but each time some major issue made us abort. (Personal illness on the road, Hurricanes, Covid, etc....). Finally did a 3 weeker this past August, but hoteling, not camping.
For PEI, it is free to get on the Island (bridge or ferry), but you pay a lot to leave. Free ferry spots are very limited, first-come. Or pay (a lot) for a guaranteed spot.
As advertised, the entire region can be extremely scenic. Off highway, most roads are excellent 2-lane setups. Easy driving, but better used by establishing base camps and exploring just using the tow vehicle. Count on a lot of driving - it is a huge area.
We were surprised by: The generally light amount of traffic, even during peak tourist times. VERY little to no "tourist trap" areas - even Cavendish and the Anne of GG thing was very restrained. Sure, attractions, a handful of gift shops, etc. - but not at all like the over-the-top so often found here in the States. West half of PEI is actually pretty flat, and devoted to huge swaths of potato fields. Look for the "small" attractions - The Bottle Houses, the Potato Museum, the "Fiddlin' Fisherman tours", etc. Well worth it - but there is that driving to deal with to get between them.
Of course Hopewell Rocks have to be on the list, as well as whale watching trips in the Bay of Fundy (we did it on a 3 mast schooner). St. John's, NB has a moderate historic area nice to wander in, but about a 1/2 day diversion.
Cabot Trail has its moments - doable pulling a big RV, but no good stopping spots while in tow. We were surprised that so much of it was through heavy woods, so not as much scenic as the publicity implies - but when it does happen, it is worth it.
Halifax, NS has a neat waterfront attractions area - museums, shops, food stands, tours. We spent 3 days taking the "duck" tours, going to the museums, etc. Did not make it to the nearby areas - Peggy's Cove, etc. unfortunately. Very "do-able" as day trips in from an outlying campground.
Almost all towns (outside the cities) are small, and very seasonal. Don't ever expect a WalMart/Home Depot resource. Small grocery stores, locally owned hardware, etc. You can always find whatever you need, but it may require a drive to the next town over, sometimes. Forget late night partying. Even in the bigger cities, expect things (restaurants, etc.) to close remarkably early.
We're from the Midwest, so late dining is not a thing. My daughters, from the East Coast, were very surprised ("What? They close at 6 or 7??")
