This approach information is provided for those who would want to backpack in as far as South Fork Pass or beyond in order to climb the four Williams summits and possibly some other unnamed summits NE of the Williams group.
From the Lost Man trailhead, hike north to Lost Man Reservoir which is about one half mile in, gaining about 200 feet elevation. Before reaching the reservoir, a little over .3 mile from the TH, another trail turns off to the left. This is Forest Service trail #1993 to Midway Pass. Use this trail to climb UN13,033 (Williams South C) or if you want to attempt a traverse of all the Williams summits from the south. Otherwise, continue north from the reservoir on the Lost Man trail for about 4.5 miles total to South Fork Pass at 11,840 ft. The trail is fairly level most of the distance, with the steepest elevation gain just prior to the pass. At about 2.4 miles up the trail, or about .4 mile past the crossing of Jack Creek is a possible campsite that lies on the east side of the trail and overlooks a section of the creek that enters a shallow, rocky gorge. The campsite is not far off the trail. Try these coordinates: N 39° 09' 02.60" W 106° 36' 37.41". However, most would probably prefer to get further up the trail before camping. Overall, there was a lack of viable campsites along this trail all the way up to the pass.
Before reaching South Fork Pass, the Lost Man trail actually turns off to the east to go up to Lost Man Lake. If interested in climbing the lowest 13er in the state, you could turn off here and hike up toward Lost Man Lake to ascend the peak. Otherwise, where the Lost Man trail turns off to the east, continue north to South Fork Pass, now just a short distance away. At the pass, if you explore over to the west of the trail, there's a very small pond with some camping possibilities at these coordinates: N 39° 10' 20.21' W 106° 35' 33.53". If you do not wish to camp here, this is the location that we used to launch off for UN13,203 (Williams South B) and also Williams Benchmark (13,312).
For Williams Mountain and UN13,108 (Williams North), continue packing north, down the trail now for about another .7 mile to a third possible campsite in the vicinity of these coordinates: N 39° 10' 44.21" W 106° 35' 01.91". This is only a very rough estimate of where we camped. The so-called campsite we used was on the west side of the trail and barely off the trail and overlooked the creek. On the east side of the trail, if you wandered up over some rock outcrops, there was evidence of a couple of other marginally used spots. This mad a good location to launch off for Williams Mountain and Un13,108 (Williams North). If you access them the way we did, you will need to continue down the trail to Deadman Lake. The terrain around Deadman Lake we found to be rather flat and wet, but there may be a viable campsite around there.