I'd prefab the emitters into a sleeved assembly on a jig, and then fit the assembly into the mortar barrel. That way, you adjust each emitter whilst in the jig and pattern it for about a basketball size impact at 10 yards. I'd imagine that would take 3 emitters or so. Then you'd know it works before you put it into the tank.

FYI, I was thinking of building some underwing emitter pylons for the old P-51. Similar to what they have up in Danville. It would take two non tankers to run it. All we need is a 5v battery source on the plane plugged into the emitters mounted on the wings. The plane gets strung up on a wire (one end on the poles on the permanent shelter, and the other to the fence). I figure we just need some standoffs on top of the plane to attach it to the wire. As to movement, there should be considerable friction on the wire, so I'd just install a cheap fishing reel to the one end of it, with the line attached to the pylon on the plan. To strafe, just reel it in. To return, (for repeated strikes) we just need to attach a fishing line on the rear of the plane, and then "cast" the reel while it gets pulled back for another run. We can build in an airstrike component to some unequal scenarios.