I rode most of the race on my own.
But then all my training is done on my own, so I'm comfortable with the solo aspect of motivating myself and pushing-on even though Watford doesn't provide much in the way of decent traing XC routes!
Even when I do shorten rides or decide on a simpler ride 1/2 way 'round a circuit (maybe 8% of my rides), strangely it always works out that it was the right decision; either my lights pack up, or the Heavens open up, or I get cramp, and then thank my Ride-Angel that I listened to her!
I think feeding and NOT running out of energy is vital for the event.
This assumes you have the legs and mental fortitude for this distance &
maybe by riding it, riders will only then know their abilities better.
In 2009 I was in a men's Vet pairs team that came 10th at Bonty 24. I rode 11 laps (it would have been 13 if my oppo' hadn't dozed off at 3am instead of riding!) I suggest to you that this was not a good enough level at that time of the year to finish this event in 2010.
Clocking up the miles is one thing, being quicker than I was in 2009 is another thing entirely. And I'll be 46 (and even uglier and fatter) next year.