Is the body an object of perception?
Absolutley.
Lets try an experiment. Look at your left hand. Feel it's presence in the present moment. Does the hand perceive, is it a knower?
The hand is not a knower, only known. This is obviously true visually, more subtly true with the tactile. It's when the hand moves and touches something that make the body seem like "something else." The sight of the hand touching something and the feel of the touch coming together conspire to make the hand seem like a sensory tool. The objects of perception they provide, are, of course, still objects, to be sure.
Is discretion an object of perception?
Discretion is just a thought, or a concept. But, at this point, so is non-discretion, or non-separation, or oneness. Though on the one hand I can imagine that all I see is a flat movie screen with colors blending, I don't need to imagine anything to see discretion. This is due to habit, and a lifetime of conceptualization, to be sure, but what I'm getting at is that discretion seems no more conceptual than non-discretion, especially becuase it requires no "imagining" (or "apparent imagining" if you like).