It’s best to avoid the “general you.”
“One would not be considered shitted,” is probably the best way I could think to word it formally.
“One would not be considered shitted” falls into the category of passive voice, which many (unjustly) frown upon. In avoiding the first and second person, and the passive voice, I might rewrite the phrase as “None shits the reader.” (None has only recently taken on plural status, but the status has gained popular acceptance, so “None shit the reader” might be more effective, depending on audience.)
But then a slight rewording, somewhat removing the subject-object dynamic in the idiom, might convey the same information: “It is not shitting one to say …”
In a technical manual, imperative mood is often preferable: “Be not shitted.” But if the present subjunctive tense might read as archaic or grandiose in the context, a different structure may be required: “Do not be shitted.”
What qualifies as formality for academia depends on instructor and assignment. If the instructor is fond of Early Modern English literature, the writer may be best served by “I nay doth shit thee.”
What qualifies as professional depends on publishing style guide—in this case refer to your company’s default style guidelines.
All that said, regardless of what overzealous secondary school English teachers might say, the first and second person are not inherently informal, and I would consider the structure “I shit you not” most straightforward, simple, and honest, as it obscures neither the actor nor the acted upon. George Orwell and E.B. White’s thoughts on language likely support this usage, and both authors are generally well-respected among English professionals and enthusiasts.
Wait, what website am I on? Tumblr? Oh. I meant, uh—I don’t even I have run out of evens. I hope Dean and Cas make out?