An engraved granite tombstone with the haiku repeated in multiple languages. Convince a lot of people to add this to their grave when they die. A cemetery is likely to remain stable as hallowed, undisturbed ground for many thousands of years. Even if future civilizations (the time frame we're talking about) forget and don't realize they're building on a burial ground, once they discover it it will be recognized as important to preserve. Burial and death rituals will likely remain preserved for 10k years. For fun, add a base64 encoded data uri representation of the haiku on the monument.