Moot point Mykester, he doesn't want to pay - but fyi, their (Heart Lake) website says differently. I've never tried to do this myself, so I can't speak from experience.
http://www.trca.on.ca/enjoy/activities/canoeing-paddling.dot
"Each park is conveniently accessible to residents and visitors in the Greater Toronto Area. Your non-motorized boats are welcomed at Albion Hills Conservation Area, Heart Lake Conservation Area and Indian Line Campground."
I think Heart Lake does allow inflatables, or maybe my eyes were playing tricks on me that day...