May not be exactly what you are looking for, but you may want to check their other larger products. I have a “Rocky” brand pack (not the Rock Mountain brand). Rocky is better known for their boots.
It’s a waist pack (fanny) and it’s very tough and durable. I’ve been using mine for about 10 years. You may want something larger yet the waist pack I use on a regular basis hiking and hunting shows little wear. I’m able to get a great deal of gear in there. Example from Deer Season: GPS, 2 sandwiches, water bottle, small thermos, camera, knife, rope, ammo, cellphone, spare gloves, maps, compass, snacks, and other small items. I was unable to find their packs online (hope they still make them) but I found a few outlets for their products within 50 miles of Hayward on the site. Darn if I can remember where I bought mine but it may have been a Fleet Farm or Gander Mountain.
What I really like about it is the ability to put the weight around my waist, I can slide it around to the front to access without taking it off, tough durable zipper pockets, excellent durable seams, strong well anchored belt and buckle that’s adjustable and it’s survived many nasty pack grabbing swamp thickets, rain storms and all the other abuse I’ve given it.
http://www.rockyboots.com/
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