Peroni climbed aboard for the second stint, holding off a charging Jayden Ojeda by just four-tenths at the chequered flag.
Brendon Leitch reached the flag first, but penalties dropped the #7 Audi from first to third.
It was a thrilling final stanza as Leitch pushed to, and at times beyond, the limits to extend a gap while Peroni was run down by Ojeda.
At the race start, Paul Stokell lead, while there was carnage in the pack.
Theo Koundouris, Stephen Grove, Marc Cini, and Shane Woodman were all caught up, Cini’s Audi R8 copping damage to the right-hand that ultimately ended his race.
Having started last, Liam Talbot benefitted heavily as he rose from 17th at the start to 11th by the end of the opening lap aboard the Ferrari 296 GT3.
Two laps later, that was ninth as he moved beyond Grove as the #1 Ferrari continued to storm through the field.
At the front of the race, Stokell was inching clear of Brad Schumacher, holding a 4.5s advantage, with Peter Hackett third.
The lead Am class entry was Garth Walden, the #45 Mercedes-AMG falling behind Talbot into seventh after 13 minutes.
Soon after, race leader Stokell lowered the lap record, logging a 1:08.865s as he continued to build a lead over Schumacher, who was beginning to fall away at around a second per lap.
That work was undone when the yellow flags were shown when Ash Samadi, spun after 17 minutes at the end of the back straight, the Audi buried in the gravel with damage to the right-rear corner.
The deployment of the Safety Car soon followed meaning, with the pit window approaching and his lead wiped out, it was a strategic disaster for Stokell.
There was worse for Schumacher, who took to the lane under the Safety Car when his Audi picked up a slow leak in the left-rear tyre.
Racing resumed with 35 minutes remaining, Stokell heading the pack from Hackett and Talbot.
The third-placed Ferrari had inherited another place from Grove, who’d toured pit lane after being embroiled in the opening corner stoush.
Barely a lap after the restart, Safety Car was back out after Darren Currie spun the #38 Aston Martin at the final corner, beaching it in the gravel.
Under the neutralisation, race control opened pit lane for the Am class drivers, the Grove car also in the lane with tape fitted to the front of the Mercedes to hold down a flapping bonnet.
Still under the Safety Car, the ProAm pit window was opened soon after, leaving Ben Schoots out front aboard the #16 Mercedes-AMG GT3 he shared with Woodman, with Paul Morris second in the #222 trophy class Scott Taylor Motorsport Porsche.
Racing resumed with the pit stop sequence complete and just over 21 minutes left on the clock.
Again, it was short-lived as Declan Fraser (#888 Mercedes-AMG GT3) appeared to make contact with Renee Gracie (#181 Audi R8 GT3) at the restart, turning the Audi sideways, leaving Grove with nowhere to go.
The Safety Car was again put into action.
Gracie had taken over the car from Stokell just moments earlier, her race and that of Brenton Grove (who’d replaced Stephen at the wheel of the #4 Mercedes), over almost as soon as it had begun.
As the field skittled around them, Chaz Mostert was off in the #1 Ferrari while Will Brown also bounced through the gravel in the #87 Audi he’d taken over from Schumacher.
Both were forced into the lane, Mostert rejoining though down the order while Brown’s Audi suffered terminal steering damage – though the team worked to keep him in the race.
Meanwhile, the #7 Audi of Leitch was handed a five-second time penalty for an unsafe release after taking the wheel from Tim Miles.
A second penalty was soon incoming for overlapping at the previous restart, leaving the Kiwi with a total of 10 seconds to be applied post-race.
The green flag waved once more with just over 10 minutes remaining, Schoots heading the pack from Morris, Leitch, and Peroni.
Morris quickly slipped to fourth, Leitch and Peroni through at Turn 1 before the pair made short work of Schoots at Turn 3.
At the front, Leitch broke the lap record with a 1:08.2, lowering it soon after to a 1:07.809s as he desperately worked to race away at the front, the Audi driver looking to cover the 10-seconds worth of penalties.
With five minutes remaining, he held a 4.1s advantage but the gap soon settled after he dropped two wheels off the road exiting Turn 1.
Though began to pull away again in the closing minutes, he ran out of time.
He took the chequered flag first but without sufficient gap to prevent the Peroni/ Rosser combination taking victory.
Jayden Ojeda rose to second in the classification about the Mercedes-AMG GT3 he shared with Paul Lucchitti.
Ojeda had reeled in Peroni in the closing minutes, setting a new lap record in the process, but could do nothing about passing the Audi.
Leitch slotted in third, with Jaxon Evans fourth in the #8 Ferrari 296 GT3 he shared with Elliott Schutte.
Schoots hung on to fifth to be the Am class winner, while Fraser got the #888 Mercedes home eighth despite a drive-through penalty, two spots ahead of Mostert in the #1 Ferrari.
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