Called LLC Ranger Station and someone from the USFS got back to me today. The portage exists. It apparently has no surprises like marshes, swamps or beaver dams. The ranger has been over it but it's been a few years. He couldn't say whether portage crews will make it to that portage this year.

I did some more research with google earth and it appears that portage sets in a little bay where someone has built a cabin just to the north of it. There is an access road that maybe cuts off 60 to 80? rods.

If I had seen that earlier, I would have asked the ranger about parking on that road and starting the portage from there. I'm not sure if it's safe to leave a vehicle there--- probably have Andersen's shuttle me over and pick me up.

I'd probably head up there, park and walk the trail first to see if I need a chainsaw to get through or a build a bog birdge over some of the apparently wetter sections.

I'm only partially kidding.  :D

I'm going to keep digging.