NOTE: Mike's time is out & back
I ran the northern section loop (Lost Coast TH of Black Sands TH and back) unsupported on 10/13/17 in 15 hours and 51 minutes. Total mileage (primarily from Strava) was 52.2 miles. Age 58. Motivations: I had planned to just run one way and knew that setting up a shuttle would just be a real pain in the butt. It then occurred to me that to do and out and back would only be around 50 miles (mileage varies depending on how far back you need to go to avoid high tide sections) and that it could easily be done in one day. I figured no one had probably ever done the northern section as a loop (out and back) before.
I do want to mention that this area is very remote and running on beach rocks has a lot of inherent risk. You should have a lot of experience on long solos, technical terrain, rescue/back up procedures, etc.
The STRAVA app photo shows the final portion until my phone died at mile 48. The straight line after that is from when the phone powered back up from the car charger many miles away and jumped directly to that point.
I have a four page detailed description of this run. I am a new user to this forum and don't know if I should add that.