I went up through Ross and over to Munro about 10 years ago.  The portage into ross and the one into Cullen starts up the creek.  They were not at that location on the maps I had.  The last portage into Mack ends by coming down a steep hill and transitions to flat rapidly.  At that point you can see the lake straight ahead down a wide beautiful path that deteriorates into a floating bog.  I got mud in my pants pockets and I never fell down.  As soon as you get to the bottom of the steep hill and can see the lake ahead make a 90° left turn.  You can find game trails that take you to the lake with less than ankle deep mud.