Ah! I (think I) get it. As long as I want to construct SQL, and my search strings look a lot like SQL in the first place. Why not let an SQL-something parse my search strings as they'll end up as my WHERE clauses anyway? SQL::Statement::Structure looks promising.

Never under-estimate the Monastery's ability to open your eyes (and gently point you to TFM). Pardon me for being dense, and thank you again.