Slapshots idea would be good too, except that it might take more programming resources to implement, and would be generally less flexible. (i.e. a latecomer couldn't up into the training/dual, etc.)
The dot command idea was originally meant for a training arena, and would allow players/Trainers to switch "opponents" while in flight (like a trainer might do). Originally (in the other sim, years ago) I only recommended damage, not general visibility, either - but of course a Tardlet who's intent on being disruptive is going to be diving in, flying in front of and/or behind and generally being disruptive to the other players even if it's just by being a visible distraction that can't do damage with his gunfire.
So for the purpose of the DA, removing both visibility and damage would be better. In a training arena, removing only damage would probably be best. (Hard to train/assist someone you can't even see until they enable you). An arena flag for whether the impact is no damage, no visibility and damage, or normal would suffice.
Truthfully though, I suspect we'll have to live with things the way they are - chances are, other tasks have priority.