Add more collision boxes to your object.
Well, all world objects have image points. At least one, the hotspot.
You can already define a collision using X and Y offset from the hotspot and angle.
Multiple collisions per behavior would just make the behavior a lot harder to use and to maintain and would probably cause a few bugs in the process. Keeping it simple helps avoid these issues.
And even though I named it collision box, given that it actually uses a sprite for collision, it can be any collision polygon a sprite allows for. So anything that isn't a circle.