Soft Sleep Normal Speed Train from Chongqing to Zhangjiaie on 23 Dec.

Generally, a cabin contains 4 sleepers. If you don't want to share with others, you need to buy the tickets of the all 4 sleepers.

Don't be such a baby. Buy 2 lower beds and you are done. If lucky, you will have empty cabin most of the time. Otherwise people will come and go. I traveled alone in soft sleeper, with my wife in hard sleeper and never had problems with privacy. Leave sex for hotel room, and other is not a problem. Chinese people taking soft sleepers are polite, won't bother you and not snoring.