If the competition among the riders wasn't a worry, the harsh battle of endurance that comes with the distance, weather and terrain should be.
The track, following a postal route established in 1224 by Ghengis Khan, spans 1000km and will put Mr Wilks on the backs of 28 semi-wild horses.
By riding around four each day over a minimum 100km - 25 different horse stations with their own vets and doctors will be set up along the course - he plans to finish the derby within the 10 day limit.
The track will take him over salt plains, into swamps and through mountains, all under the added stress of temperatures that can reach 35C in the daytime and drop below zero at nights.
"They say prepare for hot days and cold nights, but in saying that, you can get every type of weather in one day."
As a vegetarian, the Mongolian fare he'll eat out in the wild will also mean putting meat back on the menu briefly.
In the Bay of Plenty, he's been readying himself with plenty of riding at the race track and at home in Katikati.
But the longest he's been on horseback in one ride was still probably just 20km, he said.
Mr Wilks has never been one to shy away from a challenge, but the derby, kicking off next month, might tell him whether he's finally bitten off more than he can chew.
"I thought I'd give it a go and see if I could complete it, just to see whether I'm capable of it, and to see how I could push myself to the limit," he said.
"I think I like to say yes to things - and if an opportunity comes up, I don't like turning it down."
Before he ships off to Mongolia, however, Mr Wilks needs to overcome another challenge - raising enough money to get there.
On top of the $20,000 he needs to enter and to cover travel expenses, he's obliged to raise more than $2000 for the event's official charity, Cool Earth, and his chosen charity, Kiwi Care Team.
You can follow him on Facebook - Adventures of Ben Wilks - and to help with donations go to www.givealittle.co.nz adventures of Ben Wilks.
