I don't think they find every campsite as you say.  Depending on the " plan" they might not need too?

I'm guessing they'll funnel paddlers along pre-determined corridors with the afore mentioned campsites. You could day-trip off of your chosen route, but not camp.

Unless they do something like that, how can they ever enforce designated campsites?

Only way I see, is if they narrow down the areas they have too " patrol" and figure a way to check on " illegal" camping.

Maybe they have an account with Google Earth ;D