Elevation

So this is what I'll be running in California. Been trying to get this into my head. Received the Race Packet this week with all information I need. The first hour I will have to run with a headlamp..no problem! My crew person can hit many aid stations by car..perfect. I'm thinking about approaching this race as an 18 miler.
I've done plenty of 50K's this year..some hard, some not so hard..I know I have that distance in me in my sleep. Just need to maintain adequate nutrition to get to mile 32 then tackle those last 18 miles like it's a shorter race,and hopefully have some leg speed and strength left.

As far as training, of course lots of running, yoga and weight room stuff..i believe it may help plus it helps me relive stress! My body weight is at 133lbs. I know pretty low, but i hope a healthy low. I always thought I could get down to 128 or 129lbs. Just for a race not to maintain. too many people now tell me I'm to lean?