A handwritten note, politely written and personally delivered to her front door, might be better. Quoting whatever law explains that she has a legal obligation to accept your presence on the road and behave safely around you would help, as well as giving the citation to it so that she can look it up. (you could even explain that she can probably look it up herself using a combination of google and your state's legal-code website.)

Like you say, though, you have every right to be on a public street, even if it's a cul-de-sac next to the home of someone who doesn't like you.