If it is that easy to become an artillery target, you can use it to your advantage. Randomly place LoRa devices in area near the front (by autonomous or fiber optic drone drop to decrease risk). Switch and off by some random timer and see the enemy deplete its shells and drones.
Well you entering deep level of game theory here. Can you distinguish the decoy from the real and what resources you need to spend (e.g. LoRa device in a home)? How much is the signal that you can deploy decoys worth? Isn't deploying decoys below some noise level of frontline drone activity and the enemy cannot learn nothing? How many shells do you need to destroy a decoy? How certain you are about the destruction?
"the market can remain irrational longer then you can remain solvent" applies in other circumstances too.
But the wider point is generally that just because something is less effective doesn't make it useless, and just because something is effective doesn't make it dominating.
If an enemy has an artillery advantage, then shelling obvious decoys is still taking decoys off the field, which you now need to replace. But worse, their existence is giving away the fact you're active in the area, and their placement is giving away your operational range - i.e. how far can a person move on foot over rough terrain? How far in a vehicle? etc. What's the effective range of their normal infantry weapons - if you know there's a decoy then the trap has a specific radius if it is a trap.
All on the bet that they will in fact run out of shells - or in the case of drones, they won't even run out since a drone can much more easily be re-targeted.