Hi Anton,
About 10 years ago, I hiked from Florence Lk and Muir Trail Ranch on the JMT, leaving it at Charlotte Lake, and heading down Charlotte Creek. We joined the Bubbs Cr. trail and exited at Roads End/Cedar Grove in Kings Canyon. We talked with Ranger Durkee at the Charlotte Lk. R.S. and he advised us to keep to the N side of Charlotte Creek, but I don't think he'd ever gone down that way. It turned out to be a pretty gnarly x-c descent.
As we headed west from Charlotte Lake, I watched intently for any signs of trail. I found none; only signs that packers had possibly kept horses in the area for perhaps overnight stays. Anyway, I concluded that "Location Approximate" trail wasn't real. I have also scanned and looked at the area on satellite views, and surely cannot see any traces of a trail.
As for a "shortcut" northward from Charlotte Lake, the contour maps and satellite views look entirely possible to cross the 3640m (11,900') pass into Sixty Lake Basin, and from there head northwest into the Gardiner Basin. Man, the Gardiner Lakes are so remote, you can't detect even the slightest "fisherman's foot path" around the shores.
I am curious what route you might plan to take north from the Gardiner Basin, to get on with your northward trip.
Here's the
CalTopo link for the maps and images I used to look at the area.
