I have reviews for the majority of shows during that time but didn't have room for all of them in the book. I'll take a look in my files and see if there actually were any completely wilsonless shows pre 1984
While there appears not to be any specific citations on the setlist archive (or in your book), I definitely recall reading an account online from someone who had attended an early 1982 show with no Wilsons present. Carl hadn't returned (dunno if this was before or after the short run of early '82 shows where Carl returned and then left again for awhile), and this was the period where both Dennis and Brian's attendance was sporadic. It was a Foskett-era show as I recall, so it would be early '82 rather than late '81 (whatever show the account was discussing, it wasn't Sun City as far as I can remember).
Obviously no way to know for sure. Hopefully a contemporary review might shed some light, though I know reviews didn't always mentioned all members on stage, etc.