"Take only pictures, leave only footprints" has long been a basic tenet for human conduct in the wilderness. It is a slogan of some elequence as well, for its suggests that the wilderness may tolerate at least one sign of human presence.
In Quetico, campers are required to lay over in "established" campsites only. But these are not formally indicated—by map or otherwise. One must simply look for these spots; stone fireplaces are the best indicators. Your outfitter will be able to mark the best camping sites along your route.