There is the 6 mile lake - Gibson - McRae Lake canoe route just off Hwy 400 that i used to camp at 20 years ago before it became an absolute zoo (free camping will do that). Pretty sure its Gibson Lake (right side of the highway as you head north, past the Georgian Bay Rd. exit) that you can walk to a few sites without even needing a canoe. Good luck on a holiday week-end though. Better get there Wednesday because come later in the week you won't find a parking spot for miles. If you go a little further north I've seen "squatters" where the Musquash River crosses the 400, but thes people are literally 50 feet from the highway whizzing past. Rent a canoe on the way north, it will open up endless options for you. Better yet, get a real campsite, rent a boat from a local resort and enjoy yourself. Well worth the money - no fear of getting your donkey booted for trespassing and you'll catch fish!