In his short story "The Great Keinplatz Experiment", Sir Arthur Conan Doyle deals, albeit factiously, with one of the themes which is central to Wolfe's Book of the Short Sun, namely the transference of human spirits and personalities.
In the story, which appears to be set in the nineteenth century, a German professor conducts a public experiment with himself and one of his rakish young students as the subjects. The idea is that the professor will hypnotise his student using "mesmerism" so that the student's spirit will be free to leave its body. The professor will then hypnotise himself so that his spirit can interrogate that of the student to ascertain what the spirit experiences when disembodied in this fashion.
In the event, the experiment goes wrong, in that when the two spirits return to their bodies, the student's spirit ends up in the professor's body and vice versa. Niether spirit is initially aware of the transferrence and supposedly hillarious consequences ensue as the professor's body acts like the rowdy student while the sober spirit of the poor professor, ignorrant that it inhabits the body of the student, cannot understand why he is treated so disrespectfully and contemptuously by his friends and family. Eventually, the professor and student meet again and repeat the original experiment, albeit this time in private, thereby restoring their spirits to their proper bodies.
Certainly not a close parallel with TBotSS, and I'm not suggesting Conan Doyle's story as a "source" for Wolfe's book or any such thing, but it is interesting to find a treatment of this theme in an author whom Wolfe openly admires and whom he has on occasion pastiched. The common elements are the transferrence of spirits and the ignorrance of the spirits as to the fact that they are in different host bodies. Among the big differences between the two stories, apart from the vast difference in tone, style, genre and context(!) are the fact that in Wolfe's story, the migrant spirit's original body (Horn's) is dead, while the new host's body (Silk's) appears to contain two spirits, not one.
I mention it for what it worth.
Nigel