Another idea

[Corncobman]

My suggestion would be to add a script controllable tag that makes a unit not automatically targetted. They could still potentially be targetted manually.

This could be for a few units that are disguised as wreckage. I think that this would add a strategic option for surprise.

[Machiosabre]

that shouldn't be to hard, just cloaked minus the effect, on the other hand it should be fired upon when it moves so that complicates things.