I have done two of these. Las Vegas and last years HB to Carlsbad. These races are absolutly fun for the avid runner. Do not be fooled by the short distances. You should do this with people that actually run. It gets kind of tough on the second and third run.
Basically you split into two groups of six people and relay your way down to Carlsbad from Huntington. The use of vans is highly recommended. You do not want to cram yourself into a small car after running.
Running at night is interesting. You should have some idea of where you are going to run. The course is pretty well marked. Additionally, If you do a good job of calculating your teams expected time, you will be with the pack of other runners. So, good calculations are key. It sucks being at the back and they are clearing the course right behind your team.
During your breaks you should get sleep. Bring a good sleeping bag and pillow. You will most likely be sleeping on the ground. Sleep and good food is key to enjoying the journey. Luckily, I have no issues sleeping just about anywhere. So, I got plenty of sleep.
Overall it is a really fun. You get to run in places that you would normally not run. Some of the runs are very challenging. I always have a great time doing these, but I love to run. It is quite the adventure. You should try one. I am hooked.