Passport or passport card, yes, but also right now you need proof of vaccination. You can camp anywhere on crown land (basically wilderness not owned by anyone, so it's owned by the government). However you need a crown land camping permit which is about $8 a night USD, you can buy them anywhere you buy a fishing license. The backcountry is wide open for camping and fishing. Tons of deactivated logging roads that are not maintained will get you close to some lakes, and in some cases will get you right to the shoreline. Don't leave home without a chainsaw.

There are millions of miles of old roads, many of which have been reduced to ATV trails. There are probably 100,000 lakes just in Ontario alone. Remember that 90% of the Canadian population lives within 100 miles of the US border so we are talking about several million square miles of uninhabited bush.

You have to take precautions and be careful. I remember many times thinking "If I break a leg here they'll never find my body." but that adventure is part of the appeal. Fear and danger are the spices of life for some of us.