Regarding the “fantasies” and “distractions” you report, it seems to me you are dealing with these logismoi already in the best possible way: that is, by objectifying the various sensations, images, and thoughts as they arise in order to look upon them as distinct phenomena, which though they may be temporarily in you are not you.
While I certainly do not mean to trivialize the “principalities and powers” you speak of, from a methodical point of view it makes little difference whether a given thought has been planted by a demonic agency or is our own physiological or psychological construction. In either case the “disturbance” is not problematic until and unless we “couple” with it—I am using the language of the Philokalic Fathers here—and the very thought “Oh, my goodness: there is a devil in my room!” can itself lead to such “coupling”.
As the Bhagavad Gīta teaches, “There is no lustral water like unto knowledge”—the knowledge in this case that devils have no more power over us than indigestion until and unless we give it to them. For “greater is He who is in you than he who is in the world” (1 John 4:4). Spiritual virility, aristocracy, a sense of the sacred, seeing things as if in the crystalline clarity of a mountaintop vista: This is the standpoint one should make a habit of adopting, with the help of God.