Two invisible sprites on each side of your object may be the easiest solution.
You can also add two image points to the object and use "System Pick Overlapping Point" event. For example, if the image points are on sprite A and you want to check if the "right" point is overlapping sprite B:
System: Pick SpriteB Overlapping Point (SpriteA.ImagePointX("right"), SpriteA.ImagePointY("right"))