Yet the visitors had a shocking third quarter through dropped ball and the inability of hooker Sean Wanden to get his lineout throws straight under pressure, although Wanganui didn't fully capitalise as persistence with attacking the blindside by winger Samu Kubunavanua and busy reserve halfback Lindsay Horrocks was a theory that just didn't work out in muddy practice.
When they kept tight with the try-scorers in flanker Bryn Hudson and hooker Roman Tutauha, along with hard-working No8s Ranato Tikoilosomone and Malakai Volou, Wanganui got the roll on and controlled the soapy ball.
Both teams deserve credit for tackling their hearts out.
Wanganui defended in the middle portions of the second half for a solid 12 minutes in their danger zone, fullback Ace Malo somehow stopping King Country winger Dean Church from diving over at the corner flag.
For the final 15 minutes, King Country were trapped in their half but swarmed Wanganui and hit them with everything, denying reserve first-five Steelie Koro - who only rushed back at 1pm and joined the bench after Fraser Hammond dropped out with sickness - his chance to set for the dropkick.
Wanganui got one final penalty at the limit of Spooner-Neera's kicking range, but his 41m attempt, 5m from the touchline, had the distance but not quite the accuracy with time up.
Called in late after Michael Nabuliwaqa tore his calf, winger Simon Dibben was brilliant in the difficult conditions, easily making the most line breaks, while Wanganui's lineout and scrum was solid against some big country boys.
For King Country, No8 Rob Sherson got a lot of yards off the back of the scrum, although he would regret his professional foul sinbinning right before half-time.
Lock Aarin Dunster was ready for the charge-downs and heavy contact, while halfback Zayn Tipping had a better-controlled day than both William Short and Horrocks.
Pivot Te Hata Wilbore kept the ball on the string in the first half, but began faltering in the second stanza.
Coach Jason Caskey knew under those arctic conditions his team had needed more smarts than skill.
"We didn't adjust well enough, to be fair. We tried to play too much rugby in our area of the field ... The kicking was not going where it needed to be."
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Captain Peter Rowe said the pick and drive, which became Wanganui's bread and butter attack, was as much about defence as offence, with the outside backs struggling in the conditions.
"Few opportunities were left out there. We had to attack [in tight] because they were spreading [the ball] on us ... It's not the sort of rugby we want to play, but we had to."
Tipping and Spooner-Neera traded missed penalties early, before both opposing wingers were presented with grubber kicks and the tryline begging.
For Kubunavanua, he dived while hoping to get momentum to slide over, and was pushed out, then King Country's Iliesa Tavuyara opted to keep it on the toe after flanker Anthony Wise stabbed the ball ahead following a 70m breakout run, and this proved the right choice for 7-0.
Tipping added a penalty for a big 10-0 advantage given the conditions, then Kubunavanua made amends as he soared above traffic for a brilliant take of a Spooner-Neera chip kick, and after Wanganui's pack battered the King Country's line, Tutauha dove over for 10-7. Wanganui would have been content with that at half-time, but they could not kick clear of their dangerzone and from a penalty lineout, King Country brought 12 men into the rolling maul for second-five Joe Perawiti to score.
Wilbore butchered the second half restart and from the scrum Short, centre Poasa Waqanibau and Malo all attacked, then Hudson got the legs pumping and barged his way through four tacklers beside the posts.
Neither team could crack the other on their line after that, until the 69th minute when Spooner-Neera opted for the penalty attempt in front, which set up an intense final 10 minutes where Wanganui threw phase after phase at King Country, who proved equal to the task.
Wanganui 17 (Roman Tutauha, Bryn Hudson tries; Trinity Spooner-Neera pen, 2 con) King Country 17 (Iliesa Tavuyara, Joe Perawiti tries; Zayne Tipping pen, 2 con). HT: 17-7 King Country.