I am currently enjoying the book Comedy, by Andrew Stott (Routledge, 2005). In the section on the Trickster character, he points out that Carl Jung saw the trickster archetype as a mirror of the development of human consciousness from savage to sophisticated, and as such, it was an immediate agent of chaos who ultimately is an agent of order and comic resolution (Stott, 54). The quote from Jung is from his Collected Works from 1959, though the text was probably written much earlier. Nevertheless, 1959 was just about the time Toole was formulating the ideas for Confederacy, and Jung's ideas may have been more prominent in the intellectual ferment of that time.
The quote from Jung is: "The marks of deepest unconsciousness fall away from him; instead of acting in a brutal, savage, stupid, and senseless fastion, the trickster's behavior towards the end of the cycle becomes quite useful and sensible." (Collected Works, v. 9: 266, as quoted in Stott, 54). So the concept appears to have been broadly present in literary culture at the time when Toole was creating his novel.