I've got a huge amount of footage from PBP2015 showing bike set-ups. It's all in HD, so it's possible to review detail. They split into types, those who have done many PBPs have tried and tested equipment, with lots of tape and bungee cords. Newer riders have 'purer' bikes, which follow different strands of advice, depending on resources available.
PBP requires qualifiers, so the bikes should have had a good shakedown. At LEL it's possible to start on a bike put together from advice, rather than experience.
Dan Driscoll, in this shot, has gone for lots of padding on the bars, a Rolls saddle, dynohub and battery lighting, and has a reserve drinks supply, but no mudguards, but he's from Texas.
https://goo.gl/photos/3X3n6B58yyEa1wRv7