Lost Creek Trail 1E09 currently isn’t followable after 3 miles from trailhead that starts near South Fork Campground.
SGWA is trying to re-establish the trail to Grinnell Ridge Camp and on to South Fork Trail 1E04.2. The first 3 miles are in good shape to a flat alternative camp area about 1/2 mile into the wilderness. From there you would have to cross-country to Grinnell Ridge Camp and some tough cross-country to South Fork Trail which I don’t recommend.
The alternative flat camp area is a nice spot with no water except if you cross-country down to the South Fork River about 3/4 mile away on a gentle slope except navigating to river bed slope. If not familiar with cross-country hiking then you should try to get a permit for another trailhead.