One string even slightly out of tune could ruin the evening's performance, could sever a family relationship. I had to be on my (ageing) toes.
The third element of the job was to drive the band, their manager and all their gear through the night to Auckland. We had to set off before the main act started but we would see their show the next night at Vector.
There were seven of us in all and the 12-seater mini-bus was packed to the gunwales. I, of course, remained totally sober while the passengers partied behind me.
They deserved to party: they had just performed - albeit as opening act - to a sell-out crowd. All I had done was sweat and stress out over tuning guitars and delivering the right one at the right time.
Thanks to the kindness of a friend, we were able to snatch a few hours' sleep in a Turangi holiday home to break the journey. You may think that even minor "pop stars" earn enough to stay in swanky hotels. They don't. They can easily spend most of their total fee on necessary expenses.
On the road again bright and early, I became aware of how much these guys knew about the road food of this country. They have to travel so much in search of exposure that they develop an incredible knowledge of what's on offer at all hours: best burgers, best KFC in the country, freshly-squeezed juices to die for, the most moreish melting moments, worst coffee in the world.
Here's a coffee tip from a Wellington-based band: if you're outside Wellington, it's worth paying the supplement for an extra shot of coffee.
We arrived in Auckland on time for load-in but were met by bad news. The trucks from Wellington had been delayed. Progress looked hours behind what it had been the previous night. End result - no time to sound check supporting band. All part of the game.
So what have I learned from this exhausting experience? What are the "themes" of this slight little piece?
I have learned that talented young bands work astonishingly hard to pursue their dream. Even while they are being driven to the next gig, they can be constantly working on improving their stage presence, the drum fills, the overall EQ, their stage entry, their financial situation ...
I have learned that big name concerts have production, equipment and organisation levels that defy belief. I can only marvel at their magnitude. When I go out to a gig, all my gear fits into the back of the car: it does not require a fleet of semi-trailers and an army of workers.
The scale certainly puts a new perspective on the final ticket price.
I have also learned where to get the North Island's best almond croissants but I'm not telling.
And I have certainly learned the meaning of "tired".
So, if my son's band asked me to do it all again, what would I say?
"You betcha!"
Wyn Drabble is a teacher of English, a writer, public speaker and musician.