His adventure was pitched to the college especially pointing out the many life experiences he would have.
The final decision rested with principal Craig Stead, who, after getting some advice from the Ministry of Education, gave the green light.
But the adventure was almost over before it started when Jackson fell off his skateboard, leading to a very bad concussion.
After his recuperation, which included spending five days in a blacked-out caravan with a facemask on, the pair went on training rides totalling 800km, before heading north for the start.
The brevet is an endurance event rather than a race, with participants expected to complete the challenge in under 30 days and tick off 30 photo checkpoints.
Jackson Kelly tackles another trail.
John knew he could do it but how would Jackson fair?
"I knew it would be emotional, mental and physical so I said to Jackson that he had to ready for all those three things to go bad together because that's when people tag out.
"But he's very strong in all those three aspects."
Each rider who undertakes the brevet needs to be 100 per cent self-supported, which means taking their own tent, mattress, sleeping bag and so on.
With the route locked into their smartphones, they set off and potentially faced the most physically demanding part of the trip which was along Ninety Mile Beach [88km].
Instead of a feared headwind they had a rear/side/shoulder wind, which "was a huge relief," John said.
Jackson Kelly uses the wind to his advantage.
Throughout the brevet the pair aimed to knock off 100km a day but some days they banked more to allow some breathing space the next day.
They faced numerous challenges from accumulated exhaustion, broken gear cables, and making sure not to sleep in which would mean finishing later "which is way worse," Jackson said.
One of the toughest days was in the Big River area in Reefton when, deciding to bank more kilometres, they didn't arrive at a hut until 10pm when it was dark.
"It was very hard, really scary and technical as well," he said.
But there was a lot to embrace, from chatting to people from all walks of life to eating food from a variety of cafes and restaurants, and of course enjoying the charm of New Zealand.
"The most beautiful scenery was in Otago," Jackson said.
"One of my favourite days was when we crossed Lake Wakatipu and Walter Peak.
"That night we stayed in Mavora Lakes and I didn't put up my mattress because the moss was so soft.
"Another highlight was coming down the Crown Range [between Wanaka and Queenstown] because I was pretty proud after I had climbed it."
John said, "I loved the West Coast Wilderness Trail.
"But I think New Zealand in general can be very proud of the cycleways that have been produced.
"And the guys [Kennett brothers] that organised this created a course with so many stunning aspects."
At long last, after many days in the saddle and no rest days, the pair, named The Kelly Boys, finished at Bluff by the famous signpost - where there was a surprise in store for Jackson.
There to greet him was his mother Kim and his sister Anika, 14.
The Kelly family, from left, Anika, John, Jackson and Kim.
"We were a bit emotional when Jackson biked up to the last bit and saw us," said Kim, who is the college's head of careers and transition.
