"We're banking at 30 minutes per course.
"You watch each truck attacking each course at a time. You get to see everything, with only one [course] going at a time.
"The whole vehicle's got to get through the gate, so they've got the possibility of getting 1000 points if they get through the obstacle.
"I'm awarding these guys $10 per gate they clear, it's sort of an attendance fee."
Two of the ten obstacles will be based on quickest finishing times, with one of them able to have two trucks going at the same time.
"They're all variations, all slightly changed [on 2016]," said Cowper.
"This time make them easier to follow. More mud."
So there will be more bogs, more jumps, and vertical banks that even a person could not scramble cup, let alone a four-wheeled vehicle.
The one-off challenge is different from the official Porter Group 4x4 National Trial series, where drivers all rotate through the various obstacles at the same time, using natural hazards in the environment.
Cowper's team dig out their own obstacles adjacent to the viewing hillside on the Turakina property, so spectators can sit and watch every truck on every obstacle, rather than staying at one hazard or following their favourite around the area.
Returning from last year is the defending champion in Scott Biggs from Auckland, while the inaugural 2015 champion Andrew Gardner of Tauranga is also back for more.
Whanganui's Hamish Auret, who currently has an unassailable lead in the National Trial series with one round remaining, has finished bridesmaid to both Biggs and Gardner in the challenge and is dead keen to go one place better tomorrow.
"They're keen as to get into it. They've got nothing to lose here," said Cowper.
"We'll be into it - rain, hail or shine.
"The wetter it is, the more extreme it will be."
Even with all the safety precautions of helmets and strong roll cages there is an element of danger to the action, as Kapiti Coast driver Warren Jeffery discovered last year when he suffered spinal and abdominal injuries on a forward roll during the 'Roller Coaster' speed obstacle.
Pulling double duty will be world FMX (freestyle motocross) superstar Levi Sherwood, with the Manawatu rider getting behind the wheel of Cowper's 4x4 truck with which he won last season's national title.
Although out of his element, Sherwood has had four practice sessions on the course with co-driver Kayne Newman.
"He loves it, really enjoys it and I think he can mingle with the best," said Cowper.
"He's just has to get used to seeing through the mud - when you're clapped out in full gear."
However he is doing, Sherwood will climb out of the truck during the lunchtime break to put on a motorbike exhibition with fellow professional rider Nick Franklin from Tokoroa.
The challenge will be recorded and eventually screened in two 60 minute shows on TV3's CRC Motorsport programme.
"It's a big thing on the 4x4 calender now," Cowper said.
The event will start at around 10am on the Cowper farm, at 2278 State Highway 3, Turakina.
