This is a great spot 45.982717, -60.812483
I'm not sure about the ownership of the land but other people were picnicking and camping when we were there. Blog post - http://rollinginarv-wheelchairtraveling.blogspot.ca/2014/08/beach-boondocking.html
Don't tell everyone though! :-D It's such a nice spot that it could get really crowded if everyone finds out about it.