Way out to the lava.....

[Canuck]

Also, starting at the county viewing area is technically illegal. I have had a few geology friends get cited for trespassing. So if you do go by way of the country viewing area, leave at dawn and arrive back before 2. If you want to take a few xtra hours you can always do from the NP area, which has markers along the trail.
Be careful though. Take a GPS if you have one and bring at least 4 liters of water, good shoes and sunscreen!
Good luck to you and your company.