There are many Airbnb's in the Anderson Valley area, check those before ending your search. We got word that there is another wedding in Boonville the same weekend, so finding accommodations in Ukiah may be more fruitful. There are taxi services in Ukiah that you can schedule so you are not driving the windy roads at night.
For anyone that lives in the area, please consider carpooling or renting a shuttle bus. This will help with parking and allow you to be more care-free!
Both in Boonville and Hopland brining a tent for camping is a wonderful idea. For out of town family, there are some onsite accommodations (pre-set tents, rooms, etc) for Saturday night. Please go to the Eventbrite page below https://www.eventbrite.com/e/theo-sariah-wedding-reception-lodging-tickets-1260273655429?aff=oddtdtcreator