We've driven across Canada 5 times with RV (first two 5th, others 36ft A), plus done a couple of East to West relocation trips in a minivan back in the mid 90's. For sure we have found the roads way worse in condition over time, than a quarter century ago. Last trip in 2019 for 4 months from Alberta all the way over to the "rock" = Newfoundland and Labrador. Awesome experience but absolutely agree for NS, you will need to base camp and use a toad vehicle to explore a lot of the smaller really quaint areas/villages. I would also say the same about NFld. We found ourselves many times, headed up very very very slow roads off the main highway in our rig, only to turn around after about 20kms or less and not hit our destination. If ever we touch there again we would do what you are doing with base camps and a nimble auto.
PEI = free to cross the bridge onto the island but pay $$$'s to get back off or ferry even! Known for it's maple syrup collection from trees, potatoes (fries!), and T-Shirts dyed in their red soil = Tip, wear old shoes you can discard afterwards as they will end up stained red by the soil! Beautiful part of the country for your plans that look good.
FWIW: Downsizing makes cents on Youtube did a couple pretty neat videos on exploring NS the past year you might enjoy checking out where they stayed and what they saw maritime wise.
Happy Travels. SD.