When snapping to a point please take edges of object into consideration
"When snapping to a point, the snapping alignment depends on the position of the pointer, not the edges of the dragged object." -- A. Illustrator
...but if I could put my pointer exactly where I need it in order to get the edge of an object exactly on the margin, what's the point of the snap to feature? That is a pain in the butt. And really hard to do. I need the option of snapping the edges of the object to the margin. Spart guides do not help.
ColliderScribe from Astute Graphics does it right, but there is still a room for improvement. Check it anyway, perhaps it covers the needs you have (a paid tool though)