If I had one bit of advice for this kind of thing, based on doing it a few times and failing sometimes; it would be this;
Prepare for your conversation with Hypnos.
Hypnos is the creature that will make himself known to you as night falls. He is the God of sleep. He makes himself known when you are at your most vulnerable. You'd have just run 50-70 miles, a pretty hard effort so far.
When your heart beats slower, your breathing shallower and your temperature falls he'll come along with clever arguments as to why you should stop what you are doing and join him in his cave. He's got me twice before, he is probably responsible for more 100 mile DNFs than anything else.
Its good to go into the race with something already prepared for this guy, like when Percius chained his men to the boat and waxed his ears to save him from the Sirens song. It might be worth rehearsing your answers now. The more answers you have the more committed you'll be, the better you'll be able to beat him.
Here are some that I just thought of. You might all have your own.
Q - You've done enough for today, 70 miles is more than most people will do ever. You are still in the top 0.1%!
A - I didn't come here to be a statistic. I came here for a life experience. Now fuck off and let me have it.
Q - If you quit now you can get a good night's rest and spend tomorrow relaxing with your family.
A - Yeah, I'm really going to enjoy sitting on the sofa and hearing my little girl ask "Daddy, where's your buckle?"
Q - Merville and Rupard are beating you and they are shit! You don't want to be beaten by shit runners do you?
A - Comparing yourself to others is the quickest path to unhappiness. I will not go there.
Q - Your leg is hurting 7.6/10. It's only a matter of time before you will collapse in TOTAL PAIN!
A - Well you make the mistake of assuming that my pain is linear in time. That 7.6 may well go down. Also you forget that just by wanting that buckle more I also have the power to increase that denominator.
Q - You told everyone and blogged that you are going to do XX time, you are way off! Quit now and save some face
A - Anyone who I gain "face" with for quitting is not worth knowing. I'll defriend them just as soon as I've finished this
Q - But what are you going to tell people about your terrible time?
A - I will have a tale less boring to tell, not about how I got exactly what I expected but how I went through a shitstorm but came out clean on the other side. These kinds of stories tend to get more pints purchased for me.
Q - You are going to miss the cut offs.
A - "Going to" miss the cut-offs is not a reason for dropping. Missing the cut offs is. Let's cross that bridge if we come to it
Q - You are clearly having a shit time, why prolong it? End the suffering now!
A - Well in my experience it is suffering like this that beings about the most joy. Those prolonged times when you feel like you can't even move, that the world is conspiring against you, that you are a pathetic and useless waste of human flesh that has no right being out here with such great people. However you hold it together just enough to get through it, just enough to stagger out a finish, it might not be pretty but it will be done, and then that finish is yours forever, it becomes a lasting point of reference on which you can and will draw on forever. Persevering through adversity and coming out the other side is the greatest of gifts, because it is yours, uniquely so and can not be taken away or damaged. Life is about collecting these experiences. I feel rich because my head is full of these memories.