Our clerk says it is prohibited by statute, but I can't find anything under 42.12 or 42.03.

Perfect Plea at Page 91

"[T]he state may agree to recommend the judge order or not order a period of confinement, in one block or multiple blocks of time, in a county jail within the range specified by law."

Your clerk is probably looking at Article 2.18 of the Code of Criminal Procedure and needs to read further.

As John notes, Section 12(c) of Article 42.12 authorizes the trial court to order jail time in "small increments" (read: weekends).

An old AG opinion also said trial courts had the authority to authorize weekend service of sentences. See Tex. Att'y Gen. Op. No. H-603 (1975). That opinion, however, was based on the since-repealed Section 5 of Article 42.03 of the Texas Code of Criminal Procedure. See id.