Rebating would be extreamly time consuming and wastefull with a laser.

You would need to engrave a rebate which means rastering back and forward stepping over maybe 0.1mm at a time. The quailty would also suck and you would need to refocus the laser as you eat into the wood.

If this is a big production run have you thought about multiple machines maybe a laser to profile and then a router to rebate. you could even use a hand router. This is something I am considering for a product im making right now, sometimes its worth thinking about old techiniques rather than just thinking how can I do this with a cnc be it laser or router.