But Rotorua found their composure and hands in the ruck after Kaleb Trask had almost cut through the Hamilton defence saw the full back kick his team's first points.
Rotorua captain Jaya More then went over for the game's first try after his side had capitalised on its early forward dominance by opting for a scrum when Hamilton were penalised close to their own line.
But by half time the visitors had retaken the lead, going into the break 15-10, with two tries.
Their second proved to be the only try scoring backs' movement of the game, the ball efficiently moved from left to right for a five pointer in the corner.
Rotorua had their backs to the wall when Hamilton stretch their lead to 20-10 early in the second half, and that's when coach Simpkins played what looked like being a masterstroke, bringing on Viliami Tosi at No 8
"It's something we've been doing for the last couple of games now and he's been a bit of a game changer for us and we were obviously hoping for the same thing," said Simpkins.
After several phases of taking the ball one pass out, Rotorua reverted to keeping it tight, with Tosi going over.
A penalty pushed Hamilton's lead out to 23-17, and Trask was unlucky when a penalty attempt hit the upright and bounced away.
When Tosi struck again to score close to the posts, and Trask conversed, Rotorua went back into the lead.
The final say, though, went to Hamilton with a successful penalty goal kicked into a strong swirling wind.
"Either team could have won," said Simpkins.
"They took their opportunities and it could have gone either way, but today was Hamilton's day."
With the 15-a-side season now over, Simpkins said the focus will now shift to the school's sevens programme, and qualifying for the Condor Sevens Tournament.
"There are also the junior tournaments this week, and we will be looking for some good results there."
