See as Whistler is a CorSec security droid with enhanced sensor packages I thought his ability should be something similar to slicer tools or Intelligence agent. I.E. giving the ability to cause damage or to see where the target will move next.

For example: at the beginning of the activation phase If you have a TL on an enemy ship you may spend that TL to look at his maneuver dial. Or At the start of the Activation phase, If an enemy ship is within range 3 you may remove a stress token to assign it to an enemy ship.

Well I do not know much about their back-story so it is interesting to hear that. If you give Corran Horn "Stay on Target" then he can change his maneuver (after seeing where his opponent has gone). This becomes a red maneuver, Whistler "eats" the stress (not guaranteed) and Corran gets an action or two (if he K-Turned). So you can emulate some of what you suggest with this ability and the right card combination. The best abilities always need to be concise and easy to interpret but allow for a variety of potential outcomes.