Brochure voice says 'pristine' and 'world-class.' Local voice says which bar, which tide, and which rule will actually get you fined. Readers can tell the difference in one paragraph.
Write the address when you know it. Write 'verify this' when you don't. Label folklore as folklore. That honesty is not a weakness — it is the reason a local will trust your second book.
Pirate voice is the delivery system, not the research. The research is what makes the voice worth reading.