If that is your concern then think about it why he would bother creating fake accounts when he can just not give anyone anything of value and simply spend the rest on his own stuff.
On that note if you expect him to lie anyway then really what’s the point of an audit where even if he provided some documentation it could all be fabrication.
Unless you meant to gain access to his records through ESI? Not even sure that would work either as am unsure if it provides contract history and if yes how far away back. Even if possible it should be done on a regular basis to stay within the expiry date, whatever that might be.
I also assume he does his personal stuff on the same character as well so 1. the records might be difficult to differentiate between the two activities and 2. might not want to provide ESI access due to not wanting to reveal personal stuff.
So I don’t really see him providing ESI access nor even sure it would work even if he did.
In the end I suppose it all comes down to trust.
On that note I’ve personally witnessed him offering ships in starter and career systems back in the days when I was more active in those areas earlier in my career, completely coincidentally stumbling upon him in local or other cases seeing him pass through the system I was in at the moment, assuming en route to those systems. And also saw him interact with people who accepted the ships.
Could all this be just fraud utilizing alts or only spending a fraction on the ships while keeping the rest? Yes, it is technically possible.
Not sure if CCP actually looked into his activities before (I think he was featured in official CCP showcases such as the community beat or whatever it’s called or alike in the past, though not sure if I remember correctly), especially considering he serves as CSM right now (and not sure but maybe also did in the past) so I guess it would be reasonable if CCP took a look at him and his activities beforehand (at least based on the fact not everyone is allowed to run for CSM if I remember correctly) so there is at least a chance CCP might have discovered his fraud by now and would not give free exposure to him if it was a lie. Just an assumption though.
I guess based on that it would be easier if you asked CCP to look into this than ask evidence from him personally as even if he provided such it might be of questionable value if you expect him to be a liar anyway.

Edit: Btw as it involves rookies I would assume, despite scamming in EVE is a legit part of the game, CCP would not necessarily accept if someone exploited rookies in doing so. They have specific rookie griefing rules thus based on that maybe would take it much more seriously if someone did something like this than a simple scam, somewhat similar to how scamming and fraud related to the PLEX for good campaign was declared unacceptable and against the EULA if I remember correctly.