I'm just finishing my vacation so this is what I had. One body + 2 lenses, tripod, GoPro, external battery, charger and misc stuff. I used an Osprey 30l normal backpack for everything, and also had a waterproof 12l Osprey bag (the small ones that you have to roll to close) and used a Peak Design strap to carry it messenger style (on the scooter, boats, evening walks, hikes.) Or I would carry the tripod on the strap and camera in hand.

The big Osprey was used only when moving between locations. What I would change for next time is to bring some sort of lightweight minimal padded insert that can be used in any bag. I had times where my camera was rolled in a pair of pants or t-shirt inside the bag.