Hi! I'll have to take another look at the dummies. Unfortunately, cars have guns, and unlike turrets, guns don't have attack and ignore target mask. So this is basically the same issue as described in this thread.
So far, I've used "simple-entity-with-force" (which is considered an enemy structure and will be shelled by artillery turrets -- not good!) and "defender-capsule" (ignored by artillery, but not by vehicle guns or the player's PLD) for the dummies. Not sure what other prototypes I could try. I guess "ammo-turret" would have the same problem as "simple-entity-with-force", but I'll give it a try.
There may be another way, though (have to check Earendel's code first). In Autodrive, vehicles are assigned a target by the script each time they shoot. If AAI works the same way, I could ask Earendel to ignore my dummies. We'll see.