If jersey pockets are not enough I just run this
Kinda fucking goated i do not regret buying. Perfect for either just some extra fuel, another layer and a camera, change of clothes/shoes if im supposed to go somewhere and not look like a cyclist, or. I can fit my ultralight camping loadout in here (not as comfy as having the weight on the bike frame but pretty fuckin good)
Jersey pockets or this. This + a tailfin rack when i buy one will be enough for me to tour whatever distance i fancy and camp.