Thanks for your response. I've not considered Photoshop. I have had the thought that a simple graphics app with "tap and drag" functionality with a stylus should be able to do what I want. This could be an extremely simple software with note heads, note stems, staves (treble, bass, C clef), and any other graphics needed to make a notated score. It could be sort of a subset-software of a package, but with no MIDI playback capability. It seems to be completely off the radar of notation developers.
I guess I keep hoping that what I described already exists in some quiet corner of the apps market. My issue is that when writing music, I often want to delete or insert something. Using paper for this means recopying everything, or awkwardly drawing arrows to indicate where to insert something. Digital editing capability would make this so easy.