One light lighthouse

I was shooting a travel assignment for a magazine in the NC Outer Banks. I was determined to shoot the Hatteras lighthouse even though it wasn't on my shot list. I arrived late, I was shooting an assignment horse back riding on the beach at sunset, someone fell off a hors and was unconscious. I'll save that post for a new day. I get to the lighthouse at 8:30 PM and it's dark, very dark there is nothing on the Outer Banks so there is no ambient "city" light. After my 1st shot I thought the light house looked to dark, Oh .... I got some lights in the car. I grabbed an AB 800 and the Vagabon and ran toward the lighthouse and just took a wild guess. I new I didn't have time to card off the light so I just figured I'd retouch it out, I was running out of light. Final shot was f/2.8 @ 45sec. and 10 pops of the AB at full power with PW's.