how to travel for obese person needing at least 22 inches wide seats?

Can I purchase a luxury soft sleeper for just one person or two persons to be in? Is there a limit on how many people can share a luxury soft sleeper and if there are 3 people sharing a luxury soft sleeper would it still cost $151 per person for the T110 from Shanghai to Beijing? What if there is only one person ? Or can we purchase a luxury soft sleeper for US$312 and only have one person using it?
Similarly since the hard seats have no handles between seats, can I purchase two hard seats for one person so I have more space to sit in the two seat combined? Someone told me that each person can only buy one ticket. Is that true? Then what can I do please?