Ok, Couch to dragons back in 18 months, wow...
Maybe doable, but:
1, You won't be racing it, you should 'just' aim to survive it.
2, You should be prepared for the very real possibility of very serious injury and/or illness in the 6-12 months following the event.
I was there last year. I saw what it did and has done to people, VERY fit people - with years of running behind them.
i'm not saying that it can't be done. I think it can be. What I'm questioning is whether it should be done...
Would make a great follow up to the film from last year. I just hope the ending is a happy one!
If that is your sole aim then fine, good luck - go for it. But if you're interested in having a long, happy and healthy running carer you may want to think twice.