I'll be using a Super C AUDAX, i.e. the 9L. It's actually the Lightweight, but the size is the same. I WON'T be lugging it around the controls — I'm hatching a scheme to get me some lightweight material and make up a custom musette to fit the essentials to carry over my shoulder (i.e. bottles, brevet, extra layers, nothing else). Well under 1kg for the saddlebag, Bagman Sport and a small top-tube bag.
A quick strap can hold a baguette to the top of any bag — no need to get fancy, you'll be eating it in short order. Alternatively, just put it under the lid of the saddlebag and cinch the straps down — it won't be going anywhere. Last time I think I just put it on top of my front bag with a bungie over the top (I'm not using a front bag this time).
I'll also have a small (tiny) waterproof bag with a change of shorts and jersey strapped to the bagman in front of the bag, effectively under the saddle (the waterproof bag weighs a few grammes — think stuffsac). It will need to be accessed exactly once.
24L sounds profligate; 11L sounds more realistic.
And, FWIW, you'll still have to queue for baguettes in the café, just not quite as long as queuing for hot food in the restaurant.