The soft felty material looks whisper quiet. Most of the military belt rigs now have a MOLLE section on the back of the shoulder straps so you can attach a camelback. Do you know if these guys offer anything like that?
Not sure if they offer a hydration bladder attachment of any kind (but it’s worth giving them a call). When I’ve used one with my pack, I simply put the bladder in my pack, and run the tube up and over one of the backstraps. Works fine.