I've been watching this post for a few hours now, hoping someone will post a product link.
Oh well. So I've been toying around with the idea of disassembling the bayonet and boring out the tube to accept a small-diameter laser sight. Drill and tap a couple of holes on the side to allow for calibration, and use rubber boots on the screws to avoid damaging the laser. The only issue here would be attaching a sturdy piece of aluminum or steel to the end of the laser that would fit through the end of the tube and allow for a firm attachment to the lug.
With my metalworking skillz, it would look... like a giant turd. I have no usable experience in metalworking. But with the right gear and know-how, I think this could be a neat solution, and it would use existing parts that already fit i.e. the metal ring on the bayonet that fits around the end of the barrel.