When you cross that little stream at the rock face, you see a body of water south of it. If you look on the map it shows a stream that runs south skirting a swampy area and comes out at the southwest corner of Lonely lk.

I have no idea if that stream is passable but both times I went thru the portage once Yeh to Lonely and then Lonely to Yeh, that water looked deep enough to float a canoe?

Maybe something to consider checking out ?