There is a single receptacle and plug right in the center of the unit to remove power from the transformer, Intermatic also makes an Astronomical timer that fits right in there to adjust for DST and no need for large secondary timerModifying a corded transformer would invalidate its UL certification. With your background, you should know that.
I fail to understand the need for hardwiring; that will just make the system harder to service in the event of any problems. But what you seek is indeed available. Most any lighting/electrical supply house can supply one.