We got home yesterday from a 12,000 mile trip to the Eastern Provinces of Canada and Ontario.
My debit card was a pain to use at gas stations. Often wouldn't work or we had to go inside to pay, and often still wouldn't work. My visa NEVER had a problem.
Watch for full service lines at gas stations. At one busy station I accepted it because there was lots of traffic and it would have been hard to move to a self serve pump. The attendant did nothing but put the nozzle in. I asked if he was going to wash the windshield and he said, "I can't, I can't reach it. I'm only 5'2". We are still laughing about that one. BTW: Gas was about $5.50 a gallon wherever we went.
Debit quit working in North Carolina. We had to call and when we did the lady laughed and recited the places we'd tried to use it. They are only protecting us I suppose, but it was irritating.
Debit card worked great at ATMs for cash.
My advice: Try to use your cards but have a couple hundred dollars Canadian to back them up. We never had to use cash, but it was a comfort to know we could if we had to.
We saw icebergs in Newfoundland, and met wonderful people. Nova Scotia was delightful, as was Prince Edward Island. Quebec was also great. I used to go there on business and hated the snooty people. That was 30 years ago. We found folks very helpful there on this trip and especially liked "Oldtown Quebec City.
Newfoundlanders, they pronounce it New Fun Land are wonderful. One tent camper told us, "I try not to talk to these people because they tell me, "You don't have to sleep in that tent. Come home with us."
We boonie camped over half the time and never had a problem. Lots of countryside up there, and lots of back roads.
If you want input on the trip contact me at firstname.lastname@example.org