However, the Chiefs, made up of Thames Valley and King Country players, were able to close the gap repeatedly, trailing 26-14 at halftime and getting within five points after the break.
The Hurricanes lifted again, thanks in part to their quality depth on the bench, to lead 38-19, before the Chiefs scored another try and then camped on the home team's try-line.
Professional fouls saw the Hurricanes finish with 13 on the field after yellow cards in the 73rd and 79th minutes.
"The Chiefs were hot on attack but we managed to hang on and claim the Glen Osborne Cup for the first time," said Back.
"After that first 16-odd minutes, it was pretty tit-for-tat. The Chiefs never gave up.
"It was a great night. The Whanganui boys went up a notch from last week."
Lafo Takiari-Ah Ching captained the side from second-five and formed an outstanding combination with centre Darren Falaniko (Horowhenua-Kapiti).
In the forwards, Whanganui's Stan Puapii started at prop while Neo Tichbon was openside flanker and Tawhiwhi Karaitiana packed down at No8.
Rehimana Meihana was at halfback while Jordyn Leiasamaivao Turvey was on the wing.
Anthony Sellers and Mitai Hemi were backline reserves.
"I think now they realise what is required of them," said Back.
"They certainly developed through the series."
The Glen Osborne Cup was created for this inaugural fixture - named after the former 19-test All Black and current Whanganui constable, who started in Heartland rugby and then later played for both the Hurricanes and Chiefs franchises.
"We had a catchphrase that all roads lead to this one game," said Back.
"There's great rivalry between the Hurricanes and the Chiefs, so it's looking to be an annual fixture.
"The aim is to have it in the future, and whether it could expand into other Super clubs."
The Heartland Hurricanes were selected from the Whanganui, Horowhenua Kapiti, Poverty Bay and Wairarapa Bush U20 teams following their annual tournament, which was won by Whanganui.
The Heartland Chiefs selected a squad for this one specific match-up.
While the Blues catchment area does not have any Heartland-affiliated unions and the Highlanders only have North Otago, a Heartland Crusaders team could be an enticing possibility, being able to select a squad from Mid Canterbury, South Canterbury, Buller and West Coast.
Heartland wrap
All three of Steelform Whanganui's remaining opponents in the Bunnings Warehouse Heartland Championship round robin had a Saturday to forget in Week 5 of the competition.
The heavyweights are beginning to emerge as the competition heads towards the business end, with all four teams who played for the Meads and Lochore cups last year once again occupying the Top 4 spots on the points table.
Last year, because of Covid-19 delays, there were no semifinals - as the top two teams played off for the Meads Cup and the No 3-4 sides met for the Lochore Cup – with Steelform Whanganui's Lochore victory representing the highest season finish for that trophy winner.
This weekend they will host a Buller team which unequivocally lost its 2022 unbeaten tag at home, as Thames Valley came to Westport and steam-rolled to a 52-12 victory.
The contest was over by halftime as the visitors raised 33 unanswered points, with openside flanker Ben Stephens ultimately scoring two of their eight tries.
Both flankers and both locks dotted down for Thames Valley, who sit just behind Whanganui in third.
North Otago secured fourth after a demolition job in Oamaru - destroying Whanganui's remaining away game opponent Horowhenua Kapiti 89-23.
It was North Otago's second highest score in first-class rugby and their largest at home.
The visitors were still in it despite a high-scoring first half, down 33-16, as halfback Jack Tatu-Robertson's accurate boot kept them in touch.
But the southerners just countered three-pointers with seven-pointers, running riot in the second stanza with three-try bursts across 10-minute periods.
Fullback Inoke Naufahu and halfback Mataitini Feke each got doubles, while winger Ben McCarthy had a phenomenal afternoon with 29 points from a try and a union record of 12 conversions from the 13 tries scored.
Even a streaker running right in front of him at full time on his last attempt could not distract his aim.
Whanganui's last opponent in the round robin will be Mid Canterbury, whose Top 4 aspirations took a big hit following an upset 34-22 loss to King Country at home in Ashburton.
Despite the long trip, the visitors showed great composure to lead 21-8 at halftime, then they weathered the home side's comeback – scoring the last try after Mid Canterbury had closed to 27-22 after 64 minutes.
King Country first-five Quinn Collard also enjoyed the kicking conditions on the South Island's eastern coast, nailing five penalties and two conversions, after both teams scored three tries each.
But perhaps no team was more impressive than the unbeaten Meads Cup champs South Canterbury, who made the long trip to Masterton and blitzed Wairarapa Bush 73-19.
It was South Canterbury's 15th straight victory in the Heartland Championship, their 20th straight win over Heartland opponents if you include the five games in the 2020 Covid-effected season.
The visitors scored 11 tries on the artificial turf – with No8 Siu Kakala and fullback Liueli Simote getting two each, while first-five Sam Briggs was another to set a union record with kicks – slotting nine conversions along with a try.
Both South Canterbury and Whanganui will finish with two home games and an away match that's only a short drive to their neighbours in the rundown to the playoffs.
The most thrilling match of the round was played in Ruatoria, as Ngati Porou East Coast held on in their first defence of the Bill Osborne Taonga – 29-27 over West Coast.
The visitors swept out to a 20-7 lead with back-to-back tries in the 28th and 31st minutes, the second coming straight from the restart.
But East Coast has always had bravery in their backlines and they threw the ball around to get two tries before halftime and close to 20-17.
Two tries by their front rowers out wide after great passes saw East Coast edge ahead 29-20 by the 62nd minute, but West Coast weren't done with their own bonus point try just three minutes later.
A long-range penalty attempt deep in injury time by the visitors could have snatched the Taonga at the death, but the attempt went wide.
