Sorry, but I cannot help you with the wiring scheme you desire.

As you probably surmised the headlight wipers (on vehicles equipped with them from the factory) only function when the headlights are "on". In your case it would likely simplify things if the wipers and sprayers worked whenever you flipped the toggle switch, whether the headlights are "on" or not. Achieving a "rest position" is important because the headlight wipers look really odd when they are at some intermediate position.

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Fred Hoelzle