That sounds like a good challenge. I'm not familiar with the audax scene and the requirements for PBP qualification but I'm going to assume it's time based, based on these qualifying events?
In which case, a lot of your training (if done properly) at least will be in fat adaptation zones (Z1+2) and possibly sometimes in a state of ketosis. That I don't have a problem with, but ultimately, if you want to get from A to B as quickly as possible you'll need to fuel properly and have a very good understanding of what your body needs to do so and implement your strategy into training also. I'm kind of familiar with this as I do long distance triathlon and I'd say, the single biggest reason people don't finish Ironman events or underperform to their expectations is almost always nutritionally based.
When I'm in my build phase of training I'll be doing a lot of my training exactly how I'm gonna race, so my body is as efficient as possible in using the calories in giving it to extract as much performance as I can and to not 'hit the wall', and to hopefully get to the end as quickly as possible! This will be exactly the same approach that anyone would take that's serious about performance, from team sky to Mark Beumont who reportedly was taking a minimum of 8000 calories per day to fuel his round the world race.
To make a point of trying to go 130 miles without food is definitely going to be detrimental to your performance, I don't think you can really argue with this based on what information is readily available on optimal fuelling for endurance athletes.
The requirement is to complete a set of qualifying events within the timescales. These are not hugely demanding times, based on an average speed, but the kicker is the clock keeps running, regardless of whether you are asleep or stopped to eat. Its done unsupported so you carry your own food or stop and buy it. Fit fast racing snakes will have plenty time to eat and get some sleep. Less fit people will cut the breaks and simply keep those wheels turning. One thing that surprised me on my first audax was the sheer efficiency of the riders. Unlike on a sportive or club run they don't sprint up hills, or stand up, and they freewheel wherever possible.
I hit a wall at about 80 miles without food and if I do that it then becomes very difficult to recover. So my strategy will involve either snacking on the bike or going no more than 50 miles without a food stop. It's possible to minimise these as well though, grab, eat and run, rather than socialise and recover. People will often stop for 30 minutes when the refuelling could be completed in 10.
The very long events involve a withdrawal from the world, with nothing mattering except the road and the bike - a complete focus on the task at hand, which is scary and somehow life changing at the same time. You ask somebody a question which doesn't relate to the journey they are on towards the end of a long event and you're unlikely to get a coherent answer. In many ways it is more a mental challenge than a physical one.
So there are different strategies - from elite riders aiming for a very fast time, to wily old foxes determined to use all their skills to make it just within the timescale.
To qualify for PBP I need to complete all these events, but there is also a pre-qualification which allows you to enter sooner based on the longest official ride you did in the previous season. That was not a good season for me. I did some 200s, but none of them were registered in the way they needed to be internationally, so even completing a qualifying set of events I may find there are no places left because they have all gone to people who pre-qualified.
