I'd say the less the better...
I would definately take a spare set of brake pads - I burnt a set last year dropping down into the Umkumaas on Nick's Pass. I managed to buy a set off another rider.
Tube - one spare (per rider) is enough. I'd also not take the slime ones, they are very heavy. Take a patch kit instead. I find patching a tube quicker than trying to re-seat a tubeless tyre - so I won't even go for tubeless repair kit. I would rather keep that in my over-night box, and fix the tubeless or change to slime tyre in the evening.
The bike shops are usually very good - and they are not that expensive - I think the race organizers prevent them from charging silly prices.
Other spares I will take are things which are specific to your bike - derailleur hanger, dogbone (not sure what this is but it looks like something on an I-Drive), etc.
If you think of it - it's only another 3 days on your bike - and how often do you break your bike in any case ?
Food - there are plenty at the stops, but if you don't like donuts, take your own stuff. I will drop in a few Gu's if you use them, they are light, don't take up space, and can come in handy for sure.
I normally take some extra Cytomax and add it to my water bottle at the stops.
It's an awesome race...
