It is uncommon to be able to drive this high into the mountains. These facilities and roads to them probably exist because of a history of human activity around this site. Lower twin lake(and some others in the area) are created by human made dams. 

Schumacher is a loop of about 12 sites in open pine forest. Sites have picknick table, fire pit, and a tent pad. Most also have space for additional tents. There are two vault toilets, single seat. No water. Camps on the lake side are about 200 ft away with trails leading down to the shoreline. 

Further down the road that runs west of Lower Twin Lake are three more sites, set closer to the water. Outhouse for these are further along the road to the trail head. 

Lower Twin Lake, though constructed by a dam, is reasonable beautiful. There are pine trees around the lake, some meadows along the east shore, and round, rocky peaks around the basin. 

The road in is 20 miles of dirt in good condition. I could have made it with my Mini but the Honda CR-V was more comfortable. The road is narrow enough that when meeting oncoming traffic both need to come to a near stop and pass carefully. In a few places, one or the other must back to the closest wide spot. We passed a few people pulling trailers. Not sure if they were all the way up tot Schumaker, but could have been. Near Schumaker are some trail heads that people drive stock trailers to. So, it is a long dirt road but most cars can make it as well as people experienced driving their RV on forest service roads. 

Along the road there were multiple places for dispersed camping, including one official dispersed site. On a Sunday afternoon these were 80% full. 

To my surprise, Schumaker was nearly empty. There were a couple day-visit groups. On our first night there was only one other group in the camp ground and on our second 4 other groups. I suspect it was full over the weekend, which would imply it is mainly used by locals. 

If Schumaker is full the near by Bears Creek Pass dispersed camping will probably have space for you. 

We have the enjoyments of a nearly empty campground in sub-alpine terrain. The lake is warm enough to swim in. There are a couple trail heads for hiking near by. 

On the down side, there are lots of bugs and the weather is warm. Horse flies, black flies, and mosquitoes are all out during the day. The evening mosquiting hour is vicious. I can’t speculate about bugs in other times in the season but this year late July is bad. Despite our equipment, hanging out in camp is not comfortable. 

We spend two nights and decide to move on in hopes of finding fewer bugs, maybe at a lower elevation.