I have this Lowepro Photo Sport 200 AW and haven't found anything like it among competitors.
https://www.lowepro.com/us-en/photo-sport-bp-200-aw-ii-lp36888-config/ While I have the earlier model, it is a backpack great for dayhikes. Upper chambers, accessed from the top is for dayhike essentials - food, clothing, etc. The rear along the back is designed for a Camelback hydration bladder, but you can slide a 15" MPB in that same area (less the bladder). Lower half is for camera gear - two compartments - advertised camera with lens (24-105) and speedlight, but I substitute lens for the flash, usually a couple of primes, but have gotten a 70-200 in there. The camera section has side access, and with practice can slide the bag on one strap for sling style and access the camera while hiking.
For travel, I put all camera gear in the primary camera bag and alter the backpack (my two carry-ons) to hold other items including the MPB, also passports, medication, foreign currency envelopes, tickets etc in the top zipper pocket, Noise cancelling headphones, light jackets, etc in the upper compartment, and various electronic cables, bricks, adapters, and chargers in the camera compartments.