Parking Challenge

We are in the process of building a hostel in Hawaii, however we need to overcome an obstacle with the county planning department regarding parking. We intend to have an occupancy of 60-65 persons (mostly dorm beds but also a few privates) and we have at least 12 parking spaces on-site. The planning department has expressed concern that this is not sufficient for the number of guests we expect to house. We have a meeting scheduled very soon in which we will have the opportunity to explain our project and to present our case. We are looking to 'prove' that the majority of hostel guests coming to Hawaii are unlikely to rent cars because unlike hotels, most hostel guests will prefer to take advantage of the free shuttle service we will provide to/from the airport and also for daily island sightseeing excursions. We hope to demonstrate that statistically less than 20% of our guests will rent cars. Is anyone aware of any information/statistics available that could help substaniate this point? Also, since the county currently does not have any written code specific to hostels, we are looking to find comparable examples of county/municipal code relating to parking that would be favorable to our situation. As of now, the county has suggested that they would expect one parking space per bed, which is simply unreasonable! Any help our suggestions are appreciated. Thank you!