Smith won the opening one-hour race, finishing comfortably ahead of Auckland enduro expert Callan May, with Taupo motocross standout Brad Groombridge claiming third spot.
Groombridge won the second one-hour race, finishing ahead of May and former national enduro champion Jason Davis, of Whangamata.
Smith was forced to settle for fifth position, just behind Wellington's national moto trials champion Jake Whitaker.
At the halfway stage, Groombridge held the advantage with his two top-three placings being marginally better than Smith, but the endurocross phase was expected to be the real challenge.
Described as a "BMX track on steroids" in the press release, the course included logs and tractor tyres to make things really interesting.
Smith won the first of the sprints, finishing ahead of Whitaker, Groombridge, Davis and May.
However, disaster struck on the second ride for Smith after contact with a tractor tyre left him at the back of the field.
Calmly, the Marton rider set about hunting down Groombridge, eventually catching his main rival and forcing his way past at about the halfway stage.
When Groombridge made a mistake of his own about a minute later, Smith was able to open a gap and eventually finished the race in third place behind Whitaker and Davis, with Eketahuna's Jacob Hyslop claiming fourth and Groombridge back in fifth position.
It meant Smith finished up on top for the day, with Groombridge in second, while May filled third spot.